Kudos to you for being willing to share not just your successes but your mistakes as well so that we can learn from them and not have to make them ourselves. Thank you!!
I love you for including mistakes like this. We´re all here to learn. Your video series is a really big help in planning and designing my own future greenhouse project. Thanks!
He's almost right.... Let's say you have six 4" pipes. That's 12.57 sqin per pipe with a total of 75.4 sqr inches. The manifold should be equal to or greater than that in order to have a consistent volume between the manifold and the pipes connected to it and to prevent back pressure on the fan. A 6" inch pipe is 28.27 sqr inches... this is less than half that is needed. A 10" pipe has an area of 78.65 sqr in. A 10" pipe is needed for the manifold using reducing tees to connect to the recirculation pipes. The formula to us is pi*radius*radius. Having said that, since he is using an undersized fan for six 4" pipe he can get away with a smaller manifold. My point is that ALL components have to make sense as far as volume(based on area of opening or cross section). A 10" fan to feed a 10" manifold to feed the six 4" pipes that he buried.
@@craigberube9890 I just read the original, 3 year old post, and see that we were talking about pushing air? the same principles apply but we have to consider the source. If air then the SCFM that your fan/blower pushes will be the driving factor. If water then you'll have to consider that source. Residential water supplies will not accommodate a large manifold system. regardless of the fluid the principles remain the same; the sum of the legs off of the manifold should be equia to or less of that of the manifold in capacity. I made it simple by considering the cross section of the pipes. The lengths that you are dealing with are not important.... to short to worry about but the longer the pipe the more "drop" you'll get. Like I said before, valves are your friend in that they let you 'dial in' each leg off of the manifold.
I appreciate you sharing all that hard earned information and willing to reflect and improve the system. Please keep us posted regularly. Subscribed. Thank you.
Thanks. We've made huge progress this week, so Monday's video should be a good one. And yes, we plan to continue updating about the greenhouse and sharing data about how it is functioning - but hopefully you'll stick with us as we continued to upload about our random projects and adventures on the farm.
I applaud your efforts and look forward to seeing how it works out for you. We have a 350 sq-ft glass house and installed a slightly more primitive version of what you've built (using a barrel plenum, your exact fan mounted inside the plenum so it's quiet, and spaghetti tube configuration instead of a linear array). We used gravel around the pipes to discourage rodents from tunneling into the system. Our experience has shown that for cooling a greenhouse, circulation followed by ridge ventilation is key. Before we added two healthy circulation fans in a raceway orientation, our raised beds and the plants were getting fried and there were loads of hotspots. The circulation excites all the pockets of hot and they rise through passive vents and an exhaust fan. Our SCHS is capable of pushing out about a 10 degree differential for several hours before temps equalize and it loses its efficacy. So we time it so it operates starting at the hottest hours of the day. We chose to cool the lower air, and not pull hot air from the ridge, because that air is destined to leave anyway and there is no benefit grabbing the hottest stuff. Instead, we pull a single intake about a foot off the ground, and let our circulation fans equalize the lower height temps. Our exhaust from the system is coming out in 6 evenly distributed floor grates, so cool air is put where it might serve the best counter effect to the heat (and below our raised beds). Then in the middle of the night, when heat is preferred (San Diego has cool nights year round) we run for a few hours, thus cooling the ground (discharging the climate battery). The overall effect of our system is a nice equalizing factor that helps minimize overly hot days (in conjunction with circ, exhaust fan, and foggers) and minimize swing of coolness at night. Finally, because we wanted to conserve water, our raised beds are subsoil irrigation beds. I integrated all of the water lines with a common reservoir, and this allows periodic circulation of the water, which also helps stabilize temperatures, and this winter I threw in a 100W aquarium heater to help a little with heating beds through warm water beneath the soil.
I hope you realize that those that fault you for "learning opportunities" are far outweighed by those who who are learning from you. Thank you for taking the time to to post this so we can learn along side of you.
You really should use thermocouples to measure the air temps. The IR units are best for surface temp. readings. The plastic pipe surface that IR's read is slow to heat up or cool down, because they are plastic and thick. Wishing you success.
I am going to build a small greenhouse this summer with a climate battery. This helps me tremendously. Thank you! I look forward to seeing your progress!
I have been looking at lots of videos on green houses and like yours. I actually just finished completing a SHCS in a small 12 ft x 12 ft green house. Wish there were more videos. I am trying to figure out how to manage the system especially on hot days where the green house can get over 100 deg and cold nights where it can get below freezing during certian times of the year here in WY
What if you use smooth PVC plastic pipe and pitch it to a sump you could pump from? As a plumber I’ve run some very long sewer lines with pitch the entire length, SDR 35 PVC is thin wall sewer pipe that is easily available with fittings for many sizes.
I learned a lot from your video. Sometimes the fails are just as good to know as what works. Keep it up! I'd like to see the final greenhouse in action.
Sir, I ended up here a bit by chance and I'd like to congratulate you and your family for all the hard work you're putting together on doing these videos. thanks a lot for sharing with us all the infos, including your mistakes and the achievement.
Thanks - suppose it could have been worse. Just glad some folks took the time to share wisdom and offer critique. Got the fans up today and the system complete, but with 12+ hours of rain and 98% humidity it did nothing to run them. So we're looking forward to the next day of warmer weather to test it out.
Thanks! We're learning a lot. This is test greenhouse. We'll be building a much larger one nearby and hope to make improvements and modifications based on what we learn with this one. "Progress is progress" - great quote.
Question... For heating purposes, wouldn't it be better to pull air from the floor and push it out a higher vent pointing down? And vice versa for cooling..
I thought about this too. With the venting lower you get a mixing of air. In Southern California all air vents are in the ceiling for cooling purposes, but in Oregon all the vents are on the floor for heating in homes.
No way that exhaust was that low . If it’s that cold it will freeze your hands in seconds. Spray paint the pipe black where you’re taking the reading with infrared sensor. The information you’re providing others is priceless. Thanks! I think the new white pipe you installed on the geo battery should have been even bigger. I’m estimating the flow of ten 4” pipes would need a 12” pipe to flow that much. Of course the longer the four inch pipes are the less they can flow. But end results if you had went with 12” pipe on both inlet and exhaust manifolds you would get lots more cubic feet per hour air exchange with the same fan doing less work.
So you say that using 12” pipe to flow those 4” pipes is more efficient? Will it also work if the outlet pipes (the vertical ones) are 6"? Meaning the air goes into 6", then 12", then several 4", then 12" and then back to 6"... I am just in designing it so I would really appreciate a good advice in this matter.
What if you used an 8 inch pipe with a 4 inch pipe? Would that give "positive" pressure to the fan? Would that be a good thing or a bad thing for the system?
@@NotAsTraceable You would be amazed how fast the air drops to ground temperature in the tube. The thing to remember is its not how long the air spends inside the tube, its how long the entire greenhouse air volume spends in the tubes.
Maybe passive air flow? Black chimney to accomplish it? I knew a neighbor who got tired of waiting for his flue to warm up when using woodstove, so he painted it back, and then it always had draw available without worrying about smoke intrusion before the flue warmed. He had an opening at bottom he could push a rod to let it draw from outside when not burning woodstove, but close on cold days and the sun created warm chimney and good draw for the immediate starting of the stove.
I was thinking the same thing, but wanted to see how you made out. My system would mimic a in floor heating system with 200' loops instead of a manifold.
One of the things I struggle with these ideas, is the sheer BTU issue. Even really good geothermal systems in tight home construction have limits. In an uninsulated greenhouse, the problem of getting the volume of BTUs needed to materially impact the internal temp versus just a plain greenhouse... I'm skeptical and I haven't seen a lot of quantitative results other than folks just being excited about certain methods and undertaking the builds.
7:40 If the 4" fans were used, the heating cooling cycle would not be 'flat'. Does it need to be flat during the day if the temp can be allowed to rise during the day. The heating effect of the night would be enough that the 24 hr cycle is 'balanced' (say 8am and 8pm the temps are equal) Smaller capacity fans running 24/7/365 would be more economical while allowing the greenhouse to function all year. Would there be any difference if the intake was at ground level and after being pushed through the underground pipes the exhaust was at the peak of the greenhouse where the cooler air was mixed with the warmer air before it descended to the lower levels of the greenhouse. That would keep the warmest air for the plants, and the colder air from the ground might be cool enough the growth of the plants is stunted.
My thoughts in theory... Would be to have a larger manifold coming right off the fan equally distributed to the buried grid.. Slowing down air flow thru all the tubes trying to balance the air flow.. Giving time to enhance the heat exchange.. My thoughts are, to high of an air flow speed could heat the air because of friction... But when i set up my testing I will try to record as much info as possible... My first green house won't be the most efficient... But will be my testing center... and after testing each individual grid.. When tied together should be give the desired results..and much needed testing..
The way you test the company's claim is to do a current draw reading on the motor. If the current decreases, then they are wrong, because we always restrict three phase blower and pump motors all the time to control the current draw, and prolong the lifespan of the motors. It's volume that causes the most drag on a motor, not head pressure (outflow back-pressure) with AC motors. I'm not sure why DC motors would be any different.
Great job so far, can't wait to catch the updates, hopefully with plenty of data / numbers to share about how well it works with day to day usage! Your videos are a big help to all who are planning on trying out something similar. Personally, I need to come up with something slightly different, more of a heat sink for that endless Texan summer, but seeing clearly how you are doing things here and hopefully in the future seeing the results will be a huge help. Glad you caught the error before it was too late. These things are too costly and time consuming to invest in, only to find out you made an error, after the fact. :)
Thanks! Yes, I suspect different systems would be needed in different parts of the country, especially in Texas where you wouldn't have to contend with cold as much as heat. And yes, now that we're done with several days of digging and fixing - we're very glad we did it.
If the perforations are in the valleys you should use a circular saw to make a straight cut partway through the corrugations (not all the way through). When you install the tubes place the cut at the bottom. If you dont modify the tubing, you`ll have condensate sitting in every corrugation which will negatively impact the heating performance.
@@JohnGuest45 I saw the comment you left me along with another comment. You really seem to know your stuff. I am installing a greenhouse right now and could use some feedback. I am planning on doing a single run of 6" corrugated perforated pipe that is about 230 ft long. It starts at one end of the greenhouse then goes out into an open field, snakes, and comes back into a different end of my greenhouse. Question: Will the 6" opening with a 6" can fan rated for 420 cfm be sufficient for circulating the air inside of the greenhouse? Should I install two can fans, one at each opening where the 6" pipe comes in? Keep in mind (just to reiterate), I am doing one single long run of 231 feet with no manifold because I am at 10 feet deep (which is about a foot lower than the actual frost line for my area). In other words, this is a true geothermal greenhouse project and not a climate battery. Any feedback would be much appreciated!
Thanks for sharing the mistakes as well as the gains, I am thinking about doing the same as this for my greenhouse. Now I have not done as much research as you, but there are so many variables to consider its not even funny, there is airflow, there is thermal conductivity in comparison to flow, speed and area of your essentially , condenser, then all those variables in relationship to the size and efficiency of the greenhouse. I am sure some engineer somewhere would know exactly what questions to ask and be able to give an answer, but each variable even up to type of soil would change it. So I will probably just follow your lead, and it ought be be "close enough for govt. work". Thanks for sharing!
Unless you're getting ready to build it ASAP, I'd wait for us to share data and make design recommendations/adjustments. We've learned a LOT from the comments on our videos and would certainly do some things differently. Of course money was and is and issue.
I am always in the middle of a project, so it may be a bit further down the line before I get anything started, but if not, I think the ideas you have are still good, especially with the feedback your getting. In the end a greenhouse is good, and any improvements you make are better, may they be the ideal, most efficient? Maybe not, but its still an improvement.
Your pipes are set at 5 feet? How do you decide how deep? The geothermal underground greenhouse are set at 8 feet. I’m in North Kansas. They make 4 inch bilge air pumps 270 CFM would that work?
The 6 inch vs 4 inch is probably a little worse than 2.25 difference. (6/4 = 1.5, and the area is proportional to the square. 1.5 squared is 2.25) With fluid dynamics, and similarly with air flow, there is friction/drag in the air flow near the walls of the pipe. Thus, the effective diameter is a little smaller. Example: a 4 inch pipe has the same cross sectional area as 16 one inch pipes, but will let far more air through quicker/less pressure. Nice videos.
Corrugated is much better for humidity control. The more turbulence you have, the better it will pull water out of the air, or out of the soil, depending on the season and/or humidity. And the corrugated doesn't slow the bulk of the air down that much. And, as Bob Marley said, it makes the heat exchange more efficient.
Ideally,you should cut a straight slot along the full length of each tube partway through the corrugations. Dont cut right through the corrugations and into the pipe. Orientate the slot at the bottom when you install the pipe
Hi everyone I was hoping to get some advice on building a walipini greenhouse to get 4 seasons in a canadian winter zoned 4 boarder 3. I was wondering how usefull this would be to help
A very interesting idea, but more interesting the real efficiency of this approach, over the year. I think you need to install some UV lamp to clean the air goes from the soil (on exit), because this air will consist many bacterium and dampness - which is bad for the plants.
Same idea popular in Russia, it's called "Sunny Vegetarian by Ivanov". They also installing the greenhouse on the southern slope, which allows to correct the angle of sunlight that received by plants. Because in winter, insufficient solar energy due to the acute angle of the sun's rays. But I never seen the results of this approach, only idea. Anyway, good luck for you.
A couple observations: Hopefully you realize that your fans rated 483cfm is at 0" W.G. static pressure! As in ZERO inches of water gauge! You'll have to account for pressure drop for each foot of duct/dia. and type of duct material i.e. smooth PVC & corrugated drain. You'll have to account for pressure drop at every elbow/transition. Interesting project, looking forward to the results! Good Luck!
When the dewpoint of the greenhouse air is above the temperature of the battery (~April-October in your location...I'm also in the Piedmont area of NC) you will have condensation and then mold growing in the pipes. These systems may work well in the winter and year round in very dry climates but are a problem in the hot humid climate we live in. You may be able to use a HEPA level HVAC filter on the outlet to avoid breathing the contaminated air but a filter will add additional resistance and decrease the volume of air moving through the system.
I don't use an earth battery because of our experience with the crawlspace under our house here. We kept it open in the summer and closed through the winter for the first ~10 years we lived here. This caused a massive problem with condensation and mold and other nastiness. After a lot of remediation we now keep it sealed all the time and it is dry under there. My former career involved manufacturing heating and humidification systems for breathing gases used on mechanical ventilators in hospital ICUs and Operating rooms. I am well versed in the physics of changing water to vapor and the resulting condensation when it cools.
I`ve had mine in the ground since 2009, if its designed correctly you wont have any issues. If you go for 5 airchanges per hour you`ll be wasting your time. you need to design for a lot more than 5 ;) Your test was a little simplistic, but fwiw assuming you had 270cfm and the system is perfectly lossless, the heat transfer rate would be around 18kw per hour. Of course, as the mass heats up the differential drops and you`ll move less heat.
I can guarantee that I'm not confused about how dewpoint works and that I'm not an ME. I can also guarantee you would not want to spend much time breathing the air coming out of those pipes unfiltered as they will be pumping millions of mold spores and other potentially harmful microbes (remember Legionella?) into the air every hour after the first summer of operation. Warm moist air coming into contact with cool plastic drainage pipe buried underground will loose energy and not be able to maintain molecular humidity. The pipes will condense and collect water. This in turn creates an environment favorable to grow mold, mildew and other nastiness in the pipes. Blowing air through these moldy pipes will spread mold spores into the air inside the greenhouse. In our part of the world we have average dewpoints in the 60-70 degree range from April to October with spikes into the high 70s during tropical storms and hurricanes. Mold needs >60% RH to thrive. The RH in his pipes will be near 100% for most of the year assuming the ground temp around the pipes is around 50 degrees. A better option would be to run a network of coolant filled piping underground and circulate this fluid through heat exchangers in the greenhouse. Fluids are much better at transferring energy than air.
So for 6144 cubic feet of air your greenhouse is what size? Also I heard you must have commercial dehumidifier during the summer? I am located in New Jersey
Very informative, thank you! I'm always (not initially, mind you) sort of glad when I make mistakes because it does give you the opportunity to learn where you went wrong and gain a little more knowledge. At least you had a relatively easy fix. Carry on!
You might want to turn the fan down anyway. You might as well give the air a chance to exchange some heat as it does it's lap underground. A short section of pipe can handle a high air speed just like a fuse can handle lots of current. If you turn your fan speed down you will save money, does it heat both ends from each roof top end or does all the hot air go to one end and then traverse the greenhouse floor? I saw someone complaining that they had got this wrong and had ended up with uneven soil temps.
Don't forget. Your not neccesarly trying to circulate the entire volume of the greenhouse. You are just circulating whats hot, so really at any one time the volume of hot air is being circulated, during spring and autumn it can take some time for the roof to heat up so circulation will be slow anyway. During the summer you may want to just have a shade cloth covering. and a pullabale pvc in case of cold or overly wet spells.
@@JohnGuest45 I suppose so, at the end of the day plastic is probably the best thing you can use anyway, unless you can score a load of old cast iron mains water pipe.
Never push a fluid in a narrow space, pipe is one example, always pull it. The fluid has properties to organize itself in order to decrease resistance. If you push the fluid, instead of pulling, you are creating turbulence, as the fluid in front of the one being directly pushed, creates a resistance, according to the 3 Newtons' law, there will be reactive force back, aka known as eddies or turbulence, and eddies or the turbulence will be decreasing immensely the capability of the system to efficiently channel fluid for a give amount of energy input and given fluid channel geometry.
Sir, I dont know if you'll get to see this but thank you for the inspiration. I run a nonprofit conservation organization in PA and will be breaking ground on our greenhouse next weekend. I was wondering if you might have some time to discuss ideas and let me know if my plan is sound. Thank you!
Sorry about the delay in reply. The bottom dropped out with work off the farm. I wish I had more time at the moment, but really don't. Wish you all the best with your project!
When I was watching that video I thought the same thing.Done alot of indoor grow rooms. You could how use the fan and pull the air and save your fan life.
The average de-rating percentage for actual airflow is about three to seven percent because of "skin effect", which describes the air friction with the inner surface of the pipe. Fluid dynamics is another term where this is calculated to get actual flow rates.
That was awesome! I am a fairly new sub and have really been interested in your build. I read the comments you were talking about and it made me wonder. Thank you for showing and explaining mistakes. It is infinitely helpful for those of us looking into this type of system. A bit of humility sure goes a long way!! All the best:))
Thanks for the support via comment. We do appreciate it. Our hope is to always show the good, bad, and ugly of our adventures out here. And we certainly have no interest in putting something out there that is wrong. Just wish we had learned a bit more about this before we had to spend three full days fixing a mistake! But yes, humility goes a long way. Thanks for subbing!
Okay, I'm getting ready to build one of these Earth batteries... You have a 6" manifold on both sides? What is the reasoning behind the additional manifold other than the exhaust end connection? (Is it that you don't want individual 4" exhaust ports?) Also; why did you step up to 6" and not go with an 8" or 10" culvert pipe? (And, would that have made a difference on air pressure on the 4" pipes?) Thanks!
Derek, we're about to do a FAQ video about the greenhouse. You are absolutely right about size - if money and time hadn't been an issue, we should have scaled everything up. 6" pipes in the ground with much larger manifold pipes and fans. As it is, what we installed will no doubt help us in the fall/winter/early spring to grow cool season vegetables year round. But it cannot handle the heat in the summer. It seems clear that a larger system probably would. Ours just cannot turn over the air fast enough. But a larger system means greater cost up front and to operate, so you would have to run the numbers to see if it was worth it.
We're about to do a Q&A video about this greenhouse. Given the size of our greenhouse, what would you recommend for the system? Do you think it is possible to upsize this system enough to offset summer passive solar heat gain?
I've been looking at a lot of various heat exchangers and the 4" pipes seem to me to be the best ones to use. To get a 1 cubic foot of air into a pipe, you need about 22-25 feet. The manifold is what I am having difficulty with right now because I don't understand how manifolds work and what the limitations on manifolds are. 24" culvert pipe isn't cheap... I could do 8" culvert, but then I am not sure if this would run into the unknown variables... I ordered the "Year Round Solar Greenhouse" by Shiller and Plinke, and it gives me some pointers but it doesn't get into the technical nuts and bolts of "why" you need what you need... LDSprepper built three different varieties and uploaded them to RUclips and he doesn't have outflow manifolds... (he also had a lot of money to toss into his project). What I don't get about LDS prepper is where he gets his figures from of 10:1 or 7.5:1 of cubic feet of air inside the greenhouse to the actual amount of pipes you need to make the air exchange. His recipe is 7200 cubic feet of air is exchanged in 720' linear feet worth of corrugated 4" pipe... (And, it looks like he is using 4 rolls of the 250' 4" pipe). His other thing that he is doing is that he had 3" gravel brought in to layer his pipes with and he swears up and down about 8' deep is the sweet spot for heat transfer in his soil. (I have to guess that his hardiness zone is about 4 and his frost line is at least 48") My problem is that I'm not building a hoophouse and I'm in hardiness zone 6b where my frostline is at 24" … and I have a high clay content in the soil, and there is no way for me to get an excavator in the yard, so I have to use a 36" trencher. My water from the tap runs about 55 degrees year round and the water lines are buried about 3-4'feet below grade, so I'm pretty sure my sweet spot for the tubes to start... Anyway, I'm subscribed to your channel so I will checking your Q&A out when you post it. You guys have done a tremendous amount of work putting your up and I am glad you're troubleshooting it. (I use every hint and tip I can find).
Uploading the Q&A video as I type. Hope it answers some questions. What I can say is this - the earth battery works in that right now air temps at the exhaust/return are 30-40 degrees cooler than the intake during the heat of the day. To us, that is just really impressive. What the system is not able to do during the summer is offset the passive solar heat gain. Don't know if any earth battery system in our area (central NC) could do that efficiently or at relatively low costs. Assuming ours does what we think it will in the winter (keep temps in the greenhouse above freezing for the cost of leaving on two light bulbs) we will be REALLY happy. We do wonder what slightly larger manifolds and fans would have done. Have to assume higher exchange rates would mean better results for not much more money to install or run.
😂 Yes, please keep the snow up your way! And definitely hoping anyone doing this system sees this video and does this correct the first time. Digging up these ends was necessary but not exactly how I wanted to spend several days of break.
After it's all been said and done and the heat is getting higher in the greenhouse what's the final evaluation of temperature going in and temperature coming out of the pipe getting ready to set up my own system like to see what your evaluation was
The real test for this system will come in the fall and winter. What we can say right now is that it is too small to offset the tremendous thermal gain from the summer sun. Even with fans, we had to add shade cloth to reduce heat inside. That said, the air coming out of the pipes is consistently 30-40 degrees (or more) cooler. So we could see where a much larger system, one that could really exchange the volume of air quickly could work to keep it cool during the summer. The one cold night we had before spring really set in was a low of 34. The system kept the temps around 60 the entire night. So if I had to do it all over again, and could afford it, I would put in larger intake and return pipes as well as fans.
I think one step would have been to seal the insulation panels at the start, and have each panel reach above ground, the second step would have been to have gravel under each pipe layer at a inch or two per layer of pipe to help drainage in ground. I have no idea if any of that would help NC climate has a lot of moisture.
Thanks for taking the time to write and comment. Since uploading this series, we've read conflicting thoughts about the gravel. Seems most folks installing these say don't put down gravel. Aside from rain flooding the system (addressed in a future video in the series) we've had no issue with condensation filling up the system.
No, we built the greenhouse on a large flat garden area, that previous owners used for riding horses (sand on top of red clay). So when it rained there was a lot of standing water and flooded into the greenhouse - then down into the earth battery system. We just regraded and put in the start of french drains and no longer get any water in the greenhouse: ruclips.net/video/QBHKot1VBM8/видео.html and ruclips.net/video/JBJxVrZRn3M/видео.html
Who convinced you that air is a adequate heat transfer media? They lied! Use a truck radiator connected to a water pipe that you lay in a s shape in the dirt, a regular fan to move the heat from the air to the radiator and a circulation pump for the water loop and you have a system that will work both for moving heat from the air and returning it when the air cools. what you get is a thermal load that will slow both heating and cooling of your green house. Good luck. Ps. the more water you have in the system the more energy can be stored.
We really thought about that, but the board isn't structural - the pipes are. That and we weren't sure the fans would actually attach to that board. Originally thought we would put lights up there, but decided we wanted the fans a close to the ridge as possible. Thanks for the feedback though!
Threefold Farm here again. Good progress and glad to hear you made the switch to a larger manifold! Will you be monitoring the greenhouse temps once it's up? I've found it to be very helpful to monitor inlet and outlet temps as well as the temperature of the soil. In terms of cooling, I haven't seen enough cooling with our system such that we'd be able to avoid either opening the sides or door even on cool sunny spring days. The solar gain just seems to be too much. Your system may be setup better than ours. We currently use 3x 5,000CFM HAF fans to push air, but I think the static pressure causes them to behave more like 3,000CFM fans. Even with that, we're moving air about 15x/hour and aren't able to actively cool the structure. I recently started a private group for commercial "climate battery" growers on Facebook that includes a few other farms in order to share experience of what works and doesn't. I'd value your input on there if you'd like to join. Let me know and I'd be glad to add you.
Tim, we'll definitely be monitoring things once it is up and throughout the year. You're running some huge fans! We would be very interested in the FB group, as we have hope of building a much larger greenhouse and want to learn more and improve the system before we do it.
Glad to hear about monitoring! We use Acurite products to monitor ours as they're inexpensive and (relatively) reliable, plus we can view temps through our phones. We'd love to have you part of the group. I tried typing in the name of your farm to add you but couldn't find you. Perhaps you could request to join it and we'll add you that way. The group URL is facebook.com/groups/1594790417277905/ I'm currently restricting it to commercial growers as I'm really interested in the performance of larger-scale systems.
Disappointing to hear that the cooling is not as effective as hoped. I believe the 5:1 ratio rule of thumb is made up out of hot air. obviously that ratio is going to be a range, and vary dramatically with floor area vs volume, solar insolation, climate, time of year, N/S vs EW orientation etc. So you can have an 8,000 pound car with a 20 HP engine, it won't be quicker off the line than a Tesla, but it might be perfectly appropriate and functional. What you don't want is a 200 HP engine with tires, axle, transmission or clutch designed for 20 HP, OR a 20 HP engine with those designed for 200 HP, right? A simpler way to measure airflow is to use the pump curve that's published for any reputable fan. Even better if you have the watts overlaid on the pump curve. A simple "Kil o watt" meter will give you the watts, and you can compare that to the pressure with a slightly more expensive Dwyer magnehelic gauge in the appropriate range to double check your CFM, good enough for me anyway. Builditsolar is a great site for anyone doing home engineered solar anything, and home engineering is MUCH BETTER than NO ENGINEERING which, unfortunately applies to most of what's on the tube.
you should aim to put the entire greenhouse air volume underground 25-40 times per hour for effective cooling, i designed mine to handle 60 so i could experiment with the flowrate. Fit multiple sensors inside the tube to track the temperature as the air travels through, vary the flowrate and collect real data so you can base your conclusions on what is happening rather than what you imagine is happening ;). Trust me, you need a lot more fan power than you imagine to outrun the cooling capacity of a well designed installation.
John, I appreciate the info. How are your numbers calculated? I've heard anywhere from 10x/hr to 60x/hr for cooling. To get a volume like that I'd need to at least double if not triple my fans (and probably also my tubing). Do you have a working version of your house? Would love to see it and learn more about it.
If you look at the Eco Systems Design implementation of this idea, they are bringing the four-inch pipes into a 16 inch manifold tube, not a 6 inch manifold. In effect, they are able to run 16 4 inch pipes (approximate) into the 16 inch manifold while allowing full saturation of the four-inch pipes. Some quick math behind that. A 4-inch pipe has a 2-dimensional area of 12.57 square inches. A 16 inch manifold pipe has 201.06 square inches. 201.6/12.57 = 16. Your design has six 4 inch pipes? If yes, then you would need a 10 inch manifold to completely saturate the six 4 inch pipes. Area of 10 inch manifold cross-section is 78.54 square inches. 78.54 / 12.57 ~= 6.3 of the 4 inch distribution tubes.
If the 4" tubes protrude into the 16" manifold you will incur some major losses, the transition should be as aerodynamic as possible but with tubes its not always easy to do. The 10" pipe may not be big enough depending on the length. Eco systems recommend tube lengths upto 35ft wgich limits the amount of air to around 50cfm. Assuming the system has 16x 4" tubes and they all get an even share, the manifold should be designed to handle at least 800cfm with as little loss as possible. If, for example, the manifold is 20ft long you`d be better to go for a 12" manifold not a 10". Fwiw, Eco system designs are based on John Cruickshank`s original design work. Its also clear from this page that they respect and appreciate John`s great work in this field www.ecosystems-design.com/blog Its unfortunate they werent involved in the discussions on John`s "plain to sea" forurm circa 2008-2010 when collaborative testing and data collection culminated in some radical changes to the original design criteria, Some folks who had systems in the ground actually dug them back up so they could benefit from the new information. Its good that Eco systems have adopted one of the changes, which is to recommend much higher air turnover rates but seem totally unaware of the other sweeping changes. Johns website wasnt updated with the new information as he passed away in 2011. . .
Either the ground is still full of frost (what's the soil temp at duct depth) or the notoriously inaccurate infrared thermometer is whacked! You'll need that data for comparison
What kind of Grant did he get if I may ask I'm interested in doing the same thing I was hoping to build a greenhouse that is 40 feet wide and 100 ft long Underground on a cliff
There are a lot of misconceptions here. I've seen a lot of people doing this and not a single one realises that everything is done wrong. There's a lot to talk about this, but the main points are those: 1. Earth is not, and it will never be, a battery. You can't charge it with heat. The heat will dissipate fast. 2. Geothermal heat is good for winter, but has limitations, as it can't deliver more than 10-15 degreesc Celsius, depending on the location. 3. Geothermal CAN NOT be used for cooling, simply because the pvc pipes and the earth surrounding them can't transfer heat that fast. 4. In summer you vent and cool the greenhouse by opening whatever you have set up for venting. Doors, windows, top covers, etc. By doing this, you also keep the humidity in check. 5. Heating the greenouse in the winter (partially) can be done with this method, but not like you see on RUclips, but by calculating and taking into consideration the mechanics of gases, and thermodynamics. The fastest you're gonna push the air through the pipes, the less efficiency you'll have. Point 5 is the biggest mistake everybody does. Think of an indoor heating system, with water and radiators. You can't just rush the fluid through the pipes, the speed of the fluid needs to be in accordance with the heat exchanger dynamics. Also, in the ground you should have a single sinuous flexible pipe, not many straight pipes, because of the same reasons above. You have to push the air slowly to give it time to actually worm up. Also, you should keep in mind that the geothermal map of the Earth clearly shows that above 100 meters depth, there is not much change in the temperature. Also, if you have a hard winter in the location, like -20 celsius constantly, you should place the pipe lower, as the freezing will penetrate deeper into the ground. It's easy to check everything I wrote. Just run the system and measure input and output temperatures and you'll see. It's easy to follow whatever everybody is doing, because it seems to be working, but if you put science to work you'll realise very soon that a lot of those "systems" are just fancy way to spend money. This type of heating, I repeat DO NOT USE IT FOR COOLING as it doesn't work, is not used by any of the bigger food producers. They use controlled environments, and electric systems to achieve those environments. They would've been the first to cut out costs, if that was actually working !
You are missing a factor in your math. The fans will pass that amount of air with no restriction. You are passing through pipe which adds restriction plus the elbows and your manifold are creating resistance. I am wondering if you actually measured your air flow after you got everything put together. If you did I am wondering what was your loss due to the friction of the pipe? Thanks
ADS tubing wasnt designed to move air and every installation is different so the only way to figure the loss is to measure it. If you design the system for minimal loss when running an hourly flowrate equal to 60x the entire greenhouse air volume you`ll be in good shape.
JohnGuest45 Thank you for your response. I am very curious as to what you are using for your fans? What is the actual cost per hour? What were the fans rated for in air flow? What was your result when you measured your actual flow compared to what your fans were rated? What device did you use to measure your final air flow? I appreciate you taking the time to answer me as this has started a very contentious debate here. The cost per hour or energy used per hour is hour is what what we are really looking at with your actual air flow, compared to your fans rating. Again I really appreciate your time and help in this. We are looking at doing what you have done and the air flow is obviously key to this project. Thanks Tony L
JohnGuest45 John, thank you very much for all of the information and your help! This is all very much appreciated! Can you tell me what is the total linear feet of pipe you are moving air through with the fan? What were your results On the air flow testing? 1100 cfm fan rating I see that but did not see your results from the testing you did. The cost To run your energy cost the max is 300 watts but where did you land on your average draw of electric power demand? You run your fan at a constant speed 24 / 7 at xxxxx watts? You avoid peak energy demand by finding a constant speed to maintain the temperature. Your help on 3 -4 numbers is needed if you have a moment? Average energy consumption in watts? Do you have a killOwatt device in front of your fan for this? Or similar device? Average number of hours per day fans are running? You max CFM and average CFM from your fan? Thank you so much and I will try not to bother you again until we get way deeper into this project if you do not mind? Thank you again for your help! Tony L
JohnGuest45 Thank you again, we appreciate your help, feedback and time. I will be back with more questions if you are OK with that? Have a great night. Tony L
So way late now and you have probably discovered this, but you won't get that many air changes per hour due to friction in the pipes. 480 is just the fan. That corrugated pipe has particularly high friction which will reduce the flow rate several times (smooth pipe will too, just not as much).
Perhaps a more cost effective way to get some heat to the green house is a propane heater that actually produces CO2 as a combustion by product. Needless to say this has it's problems, but it will boost the CO2 levels in the winter when air circulation is a problem.
Kudos to you for being willing to share not just your successes but your mistakes as well so that we can learn from them and not have to make them ourselves. Thank you!!
I love you for including mistakes like this. We´re all here to learn. Your video series is a really big help in planning and designing my own future greenhouse project. Thanks!
He's almost right.... Let's say you have six 4" pipes. That's 12.57 sqin per pipe with a total of 75.4 sqr inches. The manifold should be equal to or greater than that in order to have a consistent volume between the manifold and the pipes connected to it and to prevent back pressure on the fan. A 6" inch pipe is 28.27 sqr inches... this is less than half that is needed. A 10" pipe has an area of 78.65 sqr in. A 10" pipe is needed for the manifold using reducing tees to connect to the recirculation pipes. The formula to us is pi*radius*radius. Having said that, since he is using an undersized fan for six 4" pipe he can get away with a smaller manifold. My point is that ALL components have to make sense as far as volume(based on area of opening or cross section). A 10" fan to feed a 10" manifold to feed the six 4" pipes that he buried.
I’m doing An 11 foot by 16 foot greenhouse . Will a 4 inch manifold connected to 4 inch pipes be ok ?
Thanks
@@craigberube9890 I just read the original, 3 year old post, and see that we were talking about pushing air? the same principles apply but we have to consider the source. If air then the SCFM that your fan/blower pushes will be the driving factor. If water then you'll have to consider that source. Residential water supplies will not accommodate a large manifold system. regardless of the fluid the principles remain the same; the sum of the legs off of the manifold should be equia to or less of that of the manifold in capacity. I made it simple by considering the cross section of the pipes. The lengths that you are dealing with are not important.... to short to worry about but the longer the pipe the more "drop" you'll get. Like I said before, valves are your friend in that they let you 'dial in' each leg off of the manifold.
@@thomasfeiller2207 , how do your numbers in the end translate in Cfm needed ?
Holy cow. That works great! I did not expect to see it drop 60+ degrees!
Thank you so much for your family's time in making these videos!
I appreciate you sharing all that hard earned information and willing to reflect and improve the system. Please keep us posted regularly. Subscribed. Thank you.
Thanks. We've made huge progress this week, so Monday's video should be a good one. And yes, we plan to continue updating about the greenhouse and sharing data about how it is functioning - but hopefully you'll stick with us as we continued to upload about our random projects and adventures on the farm.
I applaud your efforts and look forward to seeing how it works out for you. We have a 350 sq-ft glass house and installed a slightly more primitive version of what you've built (using a barrel plenum, your exact fan mounted inside the plenum so it's quiet, and spaghetti tube configuration instead of a linear array). We used gravel around the pipes to discourage rodents from tunneling into the system. Our experience has shown that for cooling a greenhouse, circulation followed by ridge ventilation is key. Before we added two healthy circulation fans in a raceway orientation, our raised beds and the plants were getting fried and there were loads of hotspots. The circulation excites all the pockets of hot and they rise through passive vents and an exhaust fan. Our SCHS is capable of pushing out about a 10 degree differential for several hours before temps equalize and it loses its efficacy. So we time it so it operates starting at the hottest hours of the day. We chose to cool the lower air, and not pull hot air from the ridge, because that air is destined to leave anyway and there is no benefit grabbing the hottest stuff. Instead, we pull a single intake about a foot off the ground, and let our circulation fans equalize the lower height temps. Our exhaust from the system is coming out in 6 evenly distributed floor grates, so cool air is put where it might serve the best counter effect to the heat (and below our raised beds). Then in the middle of the night, when heat is preferred (San Diego has cool nights year round) we run for a few hours, thus cooling the ground (discharging the climate battery). The overall effect of our system is a nice equalizing factor that helps minimize overly hot days (in conjunction with circ, exhaust fan, and foggers) and minimize swing of coolness at night.
Finally, because we wanted to conserve water, our raised beds are subsoil irrigation beds. I integrated all of the water lines with a common reservoir, and this allows periodic circulation of the water, which also helps stabilize temperatures, and this winter I threw in a 100W aquarium heater to help a little with heating beds through warm water beneath the soil.
Sounds like a great system! Any chance you would ever consider uploading a video about it?
St. Isidore's Farm that would be awesome
Come on now, San Diego needs a thermal battery? What is your 25 year low temperature for one hour? 50 degrees
I would love a copy of this video...im building a green house and every1's questioning about heat I live in VA. TIA
I hope you realize that those that fault you for "learning opportunities" are far outweighed by those who who are learning from you. Thank you for taking the time to to post this so we can learn along side of you.
Thanks for posting. We are at the point of adding the drains and now we know to go buy bigger pipe before we start
If you dont know what size pipe you need for a system, you didnt do any of the necessary calculations which doesnt bode well for the performance.
You really should use thermocouples to measure the air temps. The IR units are best for surface temp. readings. The plastic pipe surface that IR's read is slow to heat up or cool down, because they are plastic and thick. Wishing you success.
Glad you caught it now and got it corrected. Thanks for sharing! Very interesting
Yes, it's one of those things that would have nagged at us every time we went in the greenhouse. Best to just stop and deal with it now.
I am going to build a small greenhouse this summer with a climate battery. This helps me tremendously. Thank you! I look forward to seeing your progress!
Great! We're glad it could be of help!
@@joansmith3492 , it’s been 6 years for you , did you get yours built? If so how’s it been working out ?
I have been looking at lots of videos on green houses and like yours. I actually just finished completing a SHCS in a small 12 ft x 12 ft green house. Wish there were more videos. I am trying to figure out how to manage the system especially on hot days where the green house can get over 100 deg and cold nights where it can get below freezing during certian times of the year here in WY
What if you use smooth PVC plastic pipe and pitch it to a sump you could pump from? As a plumber I’ve run some very long sewer lines with pitch the entire length, SDR 35 PVC is thin wall sewer pipe that is easily available with fittings for many sizes.
I learned a lot from your video. Sometimes the fails are just as good to know as what works. Keep it up! I'd like to see the final greenhouse in action.
Thanks for the feedback. We're steady on it now. Monday's upload "should" show a mostly finished greenhouse (we hope).
Sir, I ended up here a bit by chance and I'd like to congratulate you and your family for all the hard work you're putting together on doing these videos. thanks a lot for sharing with us all the infos, including your mistakes and the achievement.
Thank you for watching and taking the time to share your kind words. Blessings to you and yours.
Where are you located to get 35F ground temp air. Did it go down to 20-30 degrees last night and the piping was exposed to the ambient air.
Sucks dude! I can't believe I missed that too! Always the little things... Glad to see you mentioned DC over AC for the fans. Thanks again for sharing
Thanks - suppose it could have been worse. Just glad some folks took the time to share wisdom and offer critique. Got the fans up today and the system complete, but with 12+ hours of rain and 98% humidity it did nothing to run them. So we're looking forward to the next day of warmer weather to test it out.
Great update. Progress is progress. Good thing you went with the higher cfm fan, as that corrugated pipe will create quite a bit of static pressure.
Thanks! We're learning a lot. This is test greenhouse. We'll be building a much larger one nearby and hope to make improvements and modifications based on what we learn with this one. "Progress is progress" - great quote.
Good man- well done. This is how we all learn, thanks.
Did you think about putting a suction fan on the outlet side?
Question...
For heating purposes, wouldn't it be better to pull air from the floor and push it out a higher vent pointing down?
And vice versa for cooling..
I thought about this too. With the venting lower you get a mixing of air. In Southern California all air vents are in the ceiling for cooling purposes, but in Oregon all the vents are on the floor for heating in homes.
No way that exhaust was that low . If it’s that cold it will freeze your hands in seconds.
Spray paint the pipe black where you’re taking the reading with infrared sensor.
The information you’re providing others is priceless. Thanks!
I think the new white pipe you installed on the geo battery should have been even bigger. I’m estimating the flow of ten 4” pipes would need a 12” pipe to flow that much. Of course the longer the four inch pipes are the less they can flow. But end results if you had went with 12” pipe on both inlet and exhaust manifolds you would get lots more cubic feet per hour air exchange with the same fan doing less work.
So you say that using 12” pipe to flow those 4” pipes is more efficient? Will it also work if the outlet pipes (the vertical ones) are 6"?
Meaning the air goes into 6", then 12", then several 4", then 12" and then back to 6"... I am just in designing it so I would really appreciate a good advice in this matter.
How did you do the calculations? Did you find an online calculator or did you do it all handrolically yourself?
How do you calculate how much pipe is needed for the square footage like how much is needed to cool down 6000 sf?
What if you used an 8 inch pipe with a 4 inch pipe? Would that give "positive" pressure to the fan?
Would that be a good thing or a bad thing for the system?
Did you consider friction loss on corogated vs smooth wall pipes?
@@NotAsTraceable
You would be amazed how fast the air drops to ground temperature in the tube. The thing to remember is its not how long the air spends inside the tube, its how long the entire greenhouse air volume spends in the tubes.
Maybe passive air flow? Black chimney to accomplish it? I knew a neighbor who got tired of waiting for his flue to warm up when using woodstove, so he painted it back, and then it always had draw available without worrying about smoke intrusion before the flue warmed. He had an opening at bottom he could push a rod to let it draw from outside when not burning woodstove, but close on cold days and the sun created warm chimney and good draw for the immediate starting of the stove.
Is this saying your ground is below 35 degrees???
Hello friends! Any update please? Did the pipes fill up with water ever?
I was thinking the same thing, but wanted to see how you made out. My system would mimic a in floor heating system with 200' loops instead of a manifold.
One of the things I struggle with these ideas, is the sheer BTU issue. Even really good geothermal systems in tight home construction have limits. In an uninsulated greenhouse, the problem of getting the volume of BTUs needed to materially impact the internal temp versus just a plain greenhouse... I'm skeptical and I haven't seen a lot of quantitative results other than folks just being excited about certain methods and undertaking the builds.
Won't you get diminishing returns as the ground around your pipes comes more in temperature equilibrium with the airflow?
7:40 If the 4" fans were used, the heating cooling cycle would not be 'flat'. Does it need to be flat during the day if the temp can be allowed to rise during the day. The heating effect of the night would be enough that the 24 hr cycle is 'balanced' (say 8am and 8pm the temps are equal) Smaller capacity fans running 24/7/365 would be more economical while allowing the greenhouse to function all year.
Would there be any difference if the intake was at ground level and after being pushed through the underground pipes the exhaust was at the peak of the greenhouse where the cooler air was mixed with the warmer air before it descended to the lower levels of the greenhouse. That would keep the warmest air for the plants, and the colder air from the ground might be cool enough the growth of the plants is stunted.
Did you ever do a final video ?
My thoughts in theory...
Would be to have a larger manifold coming right off the fan equally distributed to the buried grid..
Slowing down air flow thru all the tubes trying to balance the air flow.. Giving time to enhance the heat exchange..
My thoughts are, to high of an air flow speed could heat the air because of friction...
But when i set up my testing I will try to record as much info as possible...
My first green house won't be the most efficient...
But will be my testing center...
and after testing each individual grid..
When tied together should be give the desired results..and much needed testing..
Will you please a complete installation video from start to end with detail. Will be thankful to u alot
The way you test the company's claim is to do a current draw reading on the motor. If the current decreases, then they are wrong, because we always restrict three phase blower and pump motors all the time to control the current draw, and prolong the lifespan of the motors. It's volume that causes the most drag on a motor, not head pressure (outflow back-pressure) with AC motors. I'm not sure why DC motors would be any different.
Great job so far, can't wait to catch the updates, hopefully with plenty of data / numbers to share about how well it works with day to day usage! Your videos are a big help to all who are planning on trying out something similar. Personally, I need to come up with something slightly different, more of a heat sink for that endless Texan summer, but seeing clearly how you are doing things here and hopefully in the future seeing the results will be a huge help. Glad you caught the error before it was too late. These things are too costly and time consuming to invest in, only to find out you made an error, after the fact. :)
Thanks! Yes, I suspect different systems would be needed in different parts of the country, especially in Texas where you wouldn't have to contend with cold as much as heat. And yes, now that we're done with several days of digging and fixing - we're very glad we did it.
Nice video. Humility is grace :)
How about a link to the fans you’re going to use. How can I find them.
When laying down the perforated pipe, do you have the holes pointing upward facing the sky, or down towards the soil? Does it matter?
If the perforations are in the valleys you should use a circular saw to make a straight cut partway through the corrugations (not all the way through). When you install the tubes place the cut at the bottom. If you dont modify the tubing, you`ll have condensate sitting in every corrugation which will negatively impact the heating performance.
@@JohnGuest45 I saw the comment you left me along with another comment. You really seem to know your stuff. I am installing a greenhouse right now and could use some feedback. I am planning on doing a single run of 6" corrugated perforated pipe that is about 230 ft long. It starts at one end of the greenhouse then goes out into an open field, snakes, and comes back into a different end of my greenhouse. Question: Will the 6" opening with a 6" can fan rated for 420 cfm be sufficient for circulating the air inside of the greenhouse? Should I install two can fans, one at each opening where the 6" pipe comes in? Keep in mind (just to reiterate), I am doing one single long run of 231 feet with no manifold because I am at 10 feet deep (which is about a foot lower than the actual frost line for my area). In other words, this is a true geothermal greenhouse project and not a climate battery. Any feedback would be much appreciated!
@@sigcrypto4404
Without knowing the size and volume of the greenhouse, its impossible to say ;)
Thank you. Thank you. Thank you. Great info. Great explanation. Oh, and thanks!
I'm impressed. but where do you live that it's 114F at Easter time?
Thanks for sharing the mistakes as well as the gains, I am thinking about doing the same as this for my greenhouse. Now I have not done as much research as you, but there are so many variables to consider its not even funny, there is airflow, there is thermal conductivity in comparison to flow, speed and area of your essentially , condenser, then all those variables in relationship to the size and efficiency of the greenhouse. I am sure some engineer somewhere would know exactly what questions to ask and be able to give an answer, but each variable even up to type of soil would change it. So I will probably just follow your lead, and it ought be be "close enough for govt. work". Thanks for sharing!
Unless you're getting ready to build it ASAP, I'd wait for us to share data and make design recommendations/adjustments. We've learned a LOT from the comments on our videos and would certainly do some things differently. Of course money was and is and issue.
I am always in the middle of a project, so it may be a bit further down the line before I get anything started, but if not, I think the ideas you have are still good, especially with the feedback your getting. In the end a greenhouse is good, and any improvements you make are better, may they be the ideal, most efficient? Maybe not, but its still an improvement.
You need variable speed fans coupled to thermometers to get temp regulation
Your pipes are set at 5 feet? How do you decide how deep? The geothermal underground greenhouse are set at 8 feet. I’m in North Kansas. They make 4 inch bilge air pumps 270 CFM would that work?
Nice info thanks
About How wide and how long and height is the greenhouse that you built?
Don't remember the dimensions offhand. They're posted in the first video of this series. God bless!
The 6 inch vs 4 inch is probably a little worse than 2.25 difference. (6/4 = 1.5, and the area is proportional to the square. 1.5 squared is 2.25) With fluid dynamics, and similarly with air flow, there is friction/drag in the air flow near the walls of the pipe. Thus, the effective diameter is a little smaller. Example: a 4 inch pipe has the same cross sectional area as 16 one inch pipes, but will let far more air through quicker/less pressure.
Nice videos.
Thanks!
I presume that the fact it's cooling it is because that's a hot day? How much warming would you get on a cold day or at night?
Where do you pour in the acid?
A six inch corrugated duct is not the same as a six inch smooth duct. It has more resistance to air flow. Hope you knew that when you did your design.
Corrugated is much better for humidity control. The more turbulence you have, the better it will pull water out of the air, or out of the soil, depending on the season and/or humidity. And the corrugated doesn't slow the bulk of the air down that much. And, as Bob Marley said, it makes the heat exchange more efficient.
I'd say a smooth manifold would be better as the air would fill the smaller pipes harder
Ok. It has been 2 years. How is it working?
Paul Schimel Great! Apologies to everyone that we dropped off RUclips. Hoping to make an update video eventually.
One reason to have larger diameter fan and manifold is that smaller piping will move air faster resulting in less heat exchange
35 deg? Even in the middle of winter the air temp wont be that cold. That seems too cold to me or am i wrong
What was that website? For ecosystem design
Did You drill Your pipes to release condensing water? Maybe, it will happen that one or the other pipe fills up and breaks down airflow....
Ideally,you should cut a straight slot along the full length of each tube partway through the corrugations. Dont cut right through the corrugations and into the pipe. Orientate the slot at the bottom when you install the pipe
Merci from Montreal, Canada.
Did you glue the joints under ground ? They will leak , your ditch becomes a channel for water .
Hi everyone I was hoping to get some advice on building a walipini greenhouse to get 4 seasons in a canadian winter zoned 4 boarder 3. I was wondering how usefull this would be to help
Hello, Can this geothermal heating technique be used in cold temperatures reaching -40C at night? Thanks
Yes it can. However it will require some more engineering to keep things above freezing.
Can you water your plants without making a swimming pool?
A very interesting idea, but more interesting the real efficiency of this approach, over the year. I think you need to install some UV lamp to clean the air goes from the soil (on exit), because this air will consist many bacterium and dampness - which is bad for the plants.
Same idea popular in Russia, it's called "Sunny Vegetarian by Ivanov". They also installing the greenhouse on the southern slope, which allows to correct the angle of sunlight that received by plants. Because in winter, insufficient solar energy due to the acute angle of the sun's rays. But I never seen the results of this approach, only idea. Anyway, good luck for you.
A couple observations:
Hopefully you realize that your fans rated 483cfm is at 0" W.G. static pressure! As in ZERO inches of water gauge!
You'll have to account for pressure drop for each foot of duct/dia. and type of duct material i.e. smooth PVC & corrugated drain.
You'll have to account for pressure drop at every elbow/transition.
Interesting project, looking forward to the results!
Good Luck!
Thank you for your information and the sources!
Our pleasure!
When the dewpoint of the greenhouse air is above the temperature of the battery (~April-October in your location...I'm also in the Piedmont area of NC) you will have condensation and then mold growing in the pipes. These systems may work well in the winter and year round in very dry climates but are a problem in the hot humid climate we live in. You may be able to use a HEPA level HVAC filter on the outlet to avoid breathing the contaminated air but a filter will add additional resistance and decrease the volume of air moving through the system.
Mark Fogleman Thanks, Mark. Have you actually seen or tested for mold/spores in your system?
I don't use an earth battery because of our experience with the crawlspace under our house here. We kept it open in the summer and closed through the winter for the first ~10 years we lived here. This caused a massive problem with condensation and mold and other nastiness. After a lot of remediation we now keep it sealed all the time and it is dry under there. My former career involved manufacturing heating and humidification systems for breathing gases used on mechanical ventilators in hospital ICUs and Operating rooms. I am well versed in the physics of changing water to vapor and the resulting condensation when it cools.
Definitely something to watch out for and report back on if it becomes an issue.
I`ve had mine in the ground since 2009, if its designed correctly you wont have any issues. If you go for 5 airchanges per hour you`ll be wasting your time. you need to design for a lot more than 5 ;)
Your test was a little simplistic, but fwiw assuming you had 270cfm and the system is perfectly lossless, the heat transfer rate would be around 18kw per hour. Of course, as the mass heats up the differential drops and you`ll move less heat.
I can guarantee that I'm not confused about how dewpoint works and that I'm not an ME. I can also guarantee you would not want to spend much time breathing the air coming out of those pipes unfiltered as they will be pumping millions of mold spores and other potentially harmful microbes (remember Legionella?) into the air every hour after the first summer of operation. Warm moist air coming into contact with cool plastic drainage pipe buried underground will loose energy and not be able to maintain molecular humidity. The pipes will condense and collect water. This in turn creates an environment favorable to grow mold, mildew and other nastiness in the pipes. Blowing air through these moldy pipes will spread mold spores into the air inside the greenhouse. In our part of the world we have average dewpoints in the 60-70 degree range from April to October with spikes into the high 70s during tropical storms and hurricanes. Mold needs >60% RH to thrive. The RH in his pipes will be near 100% for most of the year assuming the ground temp around the pipes is around 50 degrees.
A better option would be to run a network of coolant filled piping underground and circulate this fluid through heat exchangers in the greenhouse. Fluids are much better at transferring energy than air.
So for 6144 cubic feet of air your greenhouse is what size? Also I heard you must have commercial dehumidifier during the summer? I am located in New Jersey
Something like 50ft x 16ft. You dont need a dehuey
Very informative, thank you! I'm always (not initially, mind you) sort of glad when I make mistakes because it does give you the opportunity to learn where you went wrong and gain a little more knowledge. At least you had a relatively easy fix. Carry on!
Couldn't agree more. Better in ways to make a mistake and learn, than have dumb luck and not really know why something worked.
St. Isidore's Farm . Absolutely. We have a saying on our land, 'hopefully we make mistakes'.
Mine saying is we do it right cause we do it twice. Lol
You might want to turn the fan down anyway. You might as well give the air a chance to exchange some heat as it does it's lap underground. A short section of pipe can handle a high air speed just like a fuse can handle lots of current. If you turn your fan speed down you will save money, does it heat both ends from each roof top end or does all the hot air go to one end and then traverse the greenhouse floor? I saw someone complaining that they had got this wrong and had ended up with uneven soil temps.
Don't forget. Your not neccesarly trying to circulate the entire volume of the greenhouse. You are just circulating whats hot, so really at any one time the volume of hot air is being circulated, during spring and autumn it can take some time for the roof to heat up so circulation will be slow anyway. During the summer you may want to just have a shade cloth covering. and a pullabale pvc in case of cold or overly wet spells.
The air in my tubes can drop over 30F in less than a second, most folks dont have enough fan power to outrun the cooling capacity of the tubes.
@@JohnGuest45 That's good to know. Surprising considering the plastic ribbed tubes are good insulators.
@@izzzzzz6
Single wall perforated drainage tube isnt much of an insulator, the corrugations increase the effective surface area considerably.
@@JohnGuest45 I suppose so, at the end of the day plastic is probably the best thing you can use anyway, unless you can score a load of old cast iron mains water pipe.
Never push a fluid in a narrow space, pipe is one example, always pull it. The fluid has properties to organize itself in order to decrease resistance. If you push the fluid, instead of pulling, you are creating turbulence, as the fluid in front of the one being directly pushed, creates a resistance, according to the 3 Newtons' law, there will be reactive force back, aka known as eddies or turbulence, and eddies or the turbulence will be decreasing immensely the capability of the system to efficiently channel fluid for a give amount of energy input and given fluid channel geometry.
Thanks for the detailed explanation.
Our pleasure - thanks for the feedback. We were worried it was too much explanation.
Sir, I dont know if you'll get to see this but thank you for the inspiration. I run a nonprofit conservation organization in PA and will be breaking ground on our greenhouse next weekend. I was wondering if you might have some time to discuss ideas and let me know if my plan is sound. Thank you!
Sorry about the delay in reply. The bottom dropped out with work off the farm. I wish I had more time at the moment, but really don't. Wish you all the best with your project!
When I was watching that video I thought the same thing.Done alot of indoor grow rooms. You could how use the fan and pull the air and save your fan life.
I'm sure you have been asked, what happens when the water table gets into your underground array of perforated pipe?
He installed French drains. You'll see his comment in answer to @cattigereyes1 below.
I am more interested in your grants. What they are for and how you qualify. I am building a below grade green house at 7000 ft.
Future Farmers of America. Youth organization through school.
The average de-rating percentage for actual airflow is about three to seven percent because of "skin effect", which describes the air friction with the inner surface of the pipe. Fluid dynamics is another term where this is calculated to get actual flow rates.
I recomend radial Fans. They can withstand nearly zero cfm at high pressure.
I apologize I'm so late to the party. what are the dimensions of your greenhouse? What fan did you end up going with? feedback?
That was awesome! I am a fairly new sub and have really been interested in your build. I read the comments you were talking about and it made me wonder. Thank you for showing and explaining mistakes. It is infinitely helpful for those of us looking into this type of system. A bit of humility sure goes a long way!! All the best:))
Thanks for the support via comment. We do appreciate it. Our hope is to always show the good, bad, and ugly of our adventures out here. And we certainly have no interest in putting something out there that is wrong. Just wish we had learned a bit more about this before we had to spend three full days fixing a mistake! But yes, humility goes a long way. Thanks for subbing!
Okay, I'm getting ready to build one of these Earth batteries... You have a 6" manifold on both sides? What is the reasoning behind the additional manifold other than the exhaust end connection? (Is it that you don't want individual 4" exhaust ports?) Also; why did you step up to 6" and not go with an 8" or 10" culvert pipe? (And, would that have made a difference on air pressure on the 4" pipes?) Thanks!
Derek, we're about to do a FAQ video about the greenhouse. You are absolutely right about size - if money and time hadn't been an issue, we should have scaled everything up. 6" pipes in the ground with much larger manifold pipes and fans. As it is, what we installed will no doubt help us in the fall/winter/early spring to grow cool season vegetables year round. But it cannot handle the heat in the summer. It seems clear that a larger system probably would. Ours just cannot turn over the air fast enough. But a larger system means greater cost up front and to operate, so you would have to run the numbers to see if it was worth it.
6" tubing is more expensive and less efficient than 4". The manifolds should be sized to handle the combined flow of all the 4" tubes ;)
We're about to do a Q&A video about this greenhouse. Given the size of our greenhouse, what would you recommend for the system? Do you think it is possible to upsize this system enough to offset summer passive solar heat gain?
I've been looking at a lot of various heat exchangers and the 4" pipes seem to me to be the best ones to use. To get a 1 cubic foot of air into a pipe, you need about 22-25 feet. The manifold is what I am having difficulty with right now because I don't understand how manifolds work and what the limitations on manifolds are. 24" culvert pipe isn't cheap... I could do 8" culvert, but then I am not sure if this would run into the unknown variables... I ordered the "Year Round Solar Greenhouse" by Shiller and Plinke, and it gives me some pointers but it doesn't get into the technical nuts and bolts of "why" you need what you need... LDSprepper built three different varieties and uploaded them to RUclips and he doesn't have outflow manifolds... (he also had a lot of money to toss into his project). What I don't get about LDS prepper is where he gets his figures from of 10:1 or 7.5:1 of cubic feet of air inside the greenhouse to the actual amount of pipes you need to make the air exchange. His recipe is 7200 cubic feet of air is exchanged in 720' linear feet worth of corrugated 4" pipe... (And, it looks like he is using 4 rolls of the 250' 4" pipe). His other thing that he is doing is that he had 3" gravel brought in to layer his pipes with and he swears up and down about 8' deep is the sweet spot for heat transfer in his soil. (I have to guess that his hardiness zone is about 4 and his frost line is at least 48") My problem is that I'm not building a hoophouse and I'm in hardiness zone 6b where my frostline is at 24" … and I have a high clay content in the soil, and there is no way for me to get an excavator in the yard, so I have to use a 36" trencher. My water from the tap runs about 55 degrees year round and the water lines are buried about 3-4'feet below grade, so I'm pretty sure my sweet spot for the tubes to start... Anyway, I'm subscribed to your channel so I will checking your Q&A out when you post it. You guys have done a tremendous amount of work putting your up and I am glad you're troubleshooting it. (I use every hint and tip I can find).
Uploading the Q&A video as I type. Hope it answers some questions. What I can say is this - the earth battery works in that right now air temps at the exhaust/return are 30-40 degrees cooler than the intake during the heat of the day. To us, that is just really impressive. What the system is not able to do during the summer is offset the passive solar heat gain. Don't know if any earth battery system in our area (central NC) could do that efficiently or at relatively low costs. Assuming ours does what we think it will in the winter (keep temps in the greenhouse above freezing for the cost of leaving on two light bulbs) we will be REALLY happy. We do wonder what slightly larger manifolds and fans would have done. Have to assume higher exchange rates would mean better results for not much more money to install or run.
Hey.. what is this short sleeve stuff? Great video and info. This will save someone some trouble down the road. Thank you for sharing this.
😂 Yes, please keep the snow up your way! And definitely hoping anyone doing this system sees this video and does this correct the first time. Digging up these ends was necessary but not exactly how I wanted to spend several days of break.
Eric you could use one of these in your climate. LOL
After it's all been said and done and the heat is getting higher in the greenhouse what's the final evaluation of temperature going in and temperature coming out of the pipe getting ready to set up my own system like to see what your evaluation was
The real test for this system will come in the fall and winter. What we can say right now is that it is too small to offset the tremendous thermal gain from the summer sun. Even with fans, we had to add shade cloth to reduce heat inside. That said, the air coming out of the pipes is consistently 30-40 degrees (or more) cooler. So we could see where a much larger system, one that could really exchange the volume of air quickly could work to keep it cool during the summer. The one cold night we had before spring really set in was a low of 34. The system kept the temps around 60 the entire night. So if I had to do it all over again, and could afford it, I would put in larger intake and return pipes as well as fans.
What entrance temperature do you have? and what temperature of exit do you have?
Isnt that too cold?
Please do a video on the complete grant acquisition process.
Excellent information!
Thank you and God bless!
I think one step would have been to seal the insulation panels at the start, and have each panel reach above ground, the second step would have been to have gravel under each pipe layer at a inch or two per layer of pipe to help drainage in ground. I have no idea if any of that would help NC climate has a lot of moisture.
Thanks for taking the time to write and comment. Since uploading this series, we've read conflicting thoughts about the gravel. Seems most folks installing these say don't put down gravel. Aside from rain flooding the system (addressed in a future video in the series) we've had no issue with condensation filling up the system.
St. Isidore's Farm confused if rain flooded the system, it means it was overloaded?
No, we built the greenhouse on a large flat garden area, that previous owners used for riding horses (sand on top of red clay). So when it rained there was a lot of standing water and flooded into the greenhouse - then down into the earth battery system. We just regraded and put in the start of french drains and no longer get any water in the greenhouse: ruclips.net/video/QBHKot1VBM8/видео.html and ruclips.net/video/JBJxVrZRn3M/видео.html
Can you please give info on the grant that your son received? My 15 yo want's to do a similar project in Utah.
Who convinced you that air is a adequate heat transfer media? They lied! Use a truck radiator connected to a water pipe that you lay in a s shape in the dirt, a regular fan to move the heat from the air to the radiator and a circulation pump for the water loop and you have a system that will work both for moving heat from the air and returning it when the air cools. what you get is a thermal load that will slow both heating and cooling of your green house. Good luck. Ps. the more water you have in the system the more energy can be stored.
About feedback, I'd rotate that toprail to have it 'stand up' that way it will hold more weight if you are going to hang stuff from it.
We really thought about that, but the board isn't structural - the pipes are. That and we weren't sure the fans would actually attach to that board. Originally thought we would put lights up there, but decided we wanted the fans a close to the ridge as possible. Thanks for the feedback though!
Threefold Farm here again. Good progress and glad to hear you made the switch to a larger manifold! Will you be monitoring the greenhouse temps once it's up? I've found it to be very helpful to monitor inlet and outlet temps as well as the temperature of the soil.
In terms of cooling, I haven't seen enough cooling with our system such that we'd be able to avoid either opening the sides or door even on cool sunny spring days. The solar gain just seems to be too much. Your system may be setup better than ours. We currently use 3x 5,000CFM HAF fans to push air, but I think the static pressure causes them to behave more like 3,000CFM fans. Even with that, we're moving air about 15x/hour and aren't able to actively cool the structure.
I recently started a private group for commercial "climate battery" growers on Facebook that includes a few other farms in order to share experience of what works and doesn't. I'd value your input on there if you'd like to join. Let me know and I'd be glad to add you.
Tim, we'll definitely be monitoring things once it is up and throughout the year. You're running some huge fans! We would be very interested in the FB group, as we have hope of building a much larger greenhouse and want to learn more and improve the system before we do it.
Glad to hear about monitoring! We use Acurite products to monitor ours as they're inexpensive and (relatively) reliable, plus we can view temps through our phones. We'd love to have you part of the group. I tried typing in the name of your farm to add you but couldn't find you. Perhaps you could request to join it and we'll add you that way. The group URL is facebook.com/groups/1594790417277905/ I'm currently restricting it to commercial growers as I'm really interested in the performance of larger-scale systems.
Disappointing to hear that the cooling is not as effective as hoped. I believe the 5:1 ratio rule of thumb is made up out of hot air. obviously that ratio is going to be a range, and vary dramatically with floor area vs volume, solar insolation, climate, time of year, N/S vs EW orientation etc. So you can have an 8,000 pound car with a 20 HP engine, it won't be quicker off the line than a Tesla, but it might be perfectly appropriate and functional. What you don't want is a 200 HP engine with tires, axle, transmission or clutch designed for 20 HP, OR a 20 HP engine with those designed for 200 HP, right?
A simpler way to measure airflow is to use the pump curve that's published for any reputable fan. Even better if you have the watts overlaid on the pump curve. A simple "Kil o watt" meter will give you the watts, and you can compare that to the pressure with a slightly more expensive Dwyer magnehelic gauge in the appropriate range to double check your CFM, good enough for me anyway. Builditsolar is a great site for anyone doing home engineered solar anything, and home engineering is MUCH BETTER than NO ENGINEERING which, unfortunately applies to most of what's on the tube.
you should aim to put the entire greenhouse air volume underground 25-40 times per hour for effective cooling, i designed mine to handle 60 so i could experiment with the flowrate. Fit multiple sensors inside the tube to track the temperature as the air travels through, vary the flowrate and collect real data so you can base your conclusions on what is happening rather than what you imagine is happening ;). Trust me, you need a lot more fan power than you imagine to outrun the cooling capacity of a well designed installation.
John, I appreciate the info. How are your numbers calculated? I've heard anywhere from 10x/hr to 60x/hr for cooling. To get a volume like that I'd need to at least double if not triple my fans (and probably also my tubing). Do you have a working version of your house? Would love to see it and learn more about it.
If you look at the Eco Systems Design implementation of this idea, they are bringing the four-inch pipes into a 16 inch manifold tube, not a 6 inch manifold. In effect, they are able to run 16 4 inch pipes (approximate) into the 16 inch manifold while allowing full saturation of the four-inch pipes. Some quick math behind that. A 4-inch pipe has a 2-dimensional area of 12.57 square inches. A 16 inch manifold pipe has 201.06 square inches. 201.6/12.57 = 16. Your design has six 4 inch pipes? If yes, then you would need a 10 inch manifold to completely saturate the six 4 inch pipes. Area of 10 inch manifold cross-section is 78.54 square inches. 78.54 / 12.57 ~= 6.3 of the 4 inch distribution tubes.
If the 4" tubes protrude into the 16" manifold you will incur some major losses, the transition should be as aerodynamic as possible but with tubes its not always easy to do.
The 10" pipe may not be big enough depending on the length. Eco systems recommend tube lengths upto 35ft wgich limits the amount of air to around 50cfm. Assuming the system has 16x 4" tubes and they all get an even share, the manifold should be designed to handle at least 800cfm with as little loss as possible. If, for example, the manifold is 20ft long you`d be better to go for a 12" manifold not a 10".
Fwiw, Eco system designs are based on John Cruickshank`s original design work. Its also clear from this page that they respect and appreciate John`s great work in this field
www.ecosystems-design.com/blog
Its unfortunate they werent involved in the discussions on John`s "plain to sea" forurm circa 2008-2010 when collaborative testing and data collection culminated in some radical changes to the original design criteria, Some folks who had systems in the ground actually dug them back up so they could benefit from the new information. Its good that Eco systems have adopted one of the changes, which is to recommend much higher air turnover rates but seem totally unaware of the other sweeping changes. Johns website wasnt updated with the new information as he passed away in 2011. .
.
Is that a closed sy?
System?
114 to 35 degrees!?!?! This is incredible!!!!
You need to know what airflow is involved before you can say its incredible :)
Either the ground is still full of frost (what's the soil temp at duct depth) or the notoriously inaccurate infrared thermometer is whacked!
You'll need that data for comparison
What kind of Grant did he get if I may ask I'm interested in doing the same thing I was hoping to build a greenhouse that is 40 feet wide and 100 ft long Underground on a cliff
There are a lot of misconceptions here. I've seen a lot of people doing this and not a single one realises that everything is done wrong. There's a lot to talk about this, but the main points are those:
1. Earth is not, and it will never be, a battery. You can't charge it with heat. The heat will dissipate fast.
2. Geothermal heat is good for winter, but has limitations, as it can't deliver more than 10-15 degreesc Celsius, depending on the location.
3. Geothermal CAN NOT be used for cooling, simply because the pvc pipes and the earth surrounding them can't transfer heat that fast.
4. In summer you vent and cool the greenhouse by opening whatever you have set up for venting. Doors, windows, top covers, etc. By doing this, you also keep the humidity in check.
5. Heating the greenouse in the winter (partially) can be done with this method, but not like you see on RUclips, but by calculating and taking into consideration the mechanics of gases, and thermodynamics. The fastest you're gonna push the air through the pipes, the less efficiency you'll have.
Point 5 is the biggest mistake everybody does. Think of an indoor heating system, with water and radiators. You can't just rush the fluid through the pipes, the speed of the fluid needs to be in accordance with the heat exchanger dynamics. Also, in the ground you should have a single sinuous flexible pipe, not many straight pipes, because of the same reasons above.
You have to push the air slowly to give it time to actually worm up. Also, you should keep in mind that the geothermal map of the Earth clearly shows that above 100 meters depth, there is not much change in the temperature. Also, if you have a hard winter in the location, like -20 celsius constantly, you should place the pipe lower, as the freezing will penetrate deeper into the ground.
It's easy to check everything I wrote. Just run the system and measure input and output temperatures and you'll see.
It's easy to follow whatever everybody is doing, because it seems to be working, but if you put science to work you'll realise very soon that a lot of those "systems" are just fancy way to spend money. This type of heating, I repeat DO NOT USE IT FOR COOLING as it doesn't work, is not used by any of the bigger food producers. They use controlled environments, and electric systems to achieve those environments. They would've been the first to cut out costs, if that was actually working !
You obviously dont understand how these systems work.
Well at least some of what you wrote has merit
You are missing a factor in your math. The fans will pass that amount of air with no restriction. You are passing through pipe which adds restriction plus the elbows and your manifold are creating resistance. I am wondering if you actually measured your air flow after you got everything put together. If you did I am wondering what was your loss due to the friction of the pipe?
Thanks
ADS tubing wasnt designed to move air and every installation is different so the only way to figure the loss is to measure it. If you design the system for minimal loss when running an hourly flowrate equal to 60x the entire greenhouse air volume you`ll be in good shape.
JohnGuest45 Thank you for your response.
I am very curious as to what you are using for your fans? What is the actual cost per hour?
What were the fans rated for in air flow? What was your result when you measured your actual flow compared to what your fans were rated?
What device did you use to measure your final air flow?
I appreciate you taking the time to answer me as this has started a very contentious debate here. The cost per hour or energy used per hour is
hour is what what we are really looking at with your actual air flow, compared to your fans rating.
Again I really appreciate your time and help in this. We are looking at doing what you have done and the air flow is obviously key to this project.
Thanks
Tony L
JohnGuest45 John, thank you very much for all of the information and your help! This is all very much appreciated!
Can you tell me what is the total linear feet of pipe you are moving air through with the fan? What were your results
On the air flow testing? 1100 cfm fan rating I see that but did not see your results from the testing you did. The cost
To run your energy cost the max is 300 watts but where did you land on your average draw of electric power demand?
You run your fan at a constant speed 24 / 7 at xxxxx watts? You avoid peak energy demand by finding a constant speed to maintain the temperature.
Your help on 3 -4 numbers is needed if you have a moment?
Average energy consumption in watts? Do you have a killOwatt device in front of your fan for this? Or similar device?
Average number of hours per day fans are running?
You max CFM and average CFM from your fan?
Thank you so much and I will try not to bother you again until we get way deeper into this project if you do not mind?
Thank you again for your help!
Tony L
JohnGuest45 Thank you again, we appreciate your help, feedback and time.
I will be back with more questions if you are OK with that?
Have a great night.
Tony L
So way late now and you have probably discovered this, but you won't get that many air changes per hour due to friction in the pipes. 480 is just the fan. That corrugated pipe has particularly high friction which will reduce the flow rate several times (smooth pipe will too, just not as much).
Thanks!
Run water instead? 3x thermal holding potential, slightly more expensive pump, similar kilowatt hours... just thinking outloud
Perhaps a more cost effective way to get some heat to the green house is a propane heater that actually produces CO2 as a combustion by product. Needless to say this has it's problems, but it will boost the CO2 levels in the winter when air circulation is a problem.