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I still have 2 in my office standing on the window sill and they work well but it is not my main heating. For me, the problem with this kind of heating is, that it only works if the sun shines so no heating at night, unless you are able to store the energy. You could store the hot air in wax, it takes up 5x more energy than water but you need much more complicated equipment to do so. I work on these projects as a hobby and change projects easily. In my experience the best tube is a tube with a diameter of 100 mm (4"), in that way you can eliminate the resistance of the airflow much better, also MUCH bigger heated surface. I enquired in China, because there is where these tubes are made but I had to order 150, did not want that.

I lost my hard drive a few months ago due to mechanical failure and lost all files. Software could not retrieve as the drive did not turn any more.

I respectfully disagree. The thing is that I extract the heat from the inside area of the tube which is at least 20x bigger than the surface of the heatsink. The sand inside is like storage but has bad transport of heat. A full copper rod would be better I guess but it was my goal to make a heat exchanger with things, cheap, simple and with materials that you can buy at any hardware store. I can get temperatures over 200C when I decrease the airflow, I did that once, but my ABS fittings burned 

Thank you for your comment. Do a search on RUclips for “self watering 5 gallon buckets”. There is a lot that is shown there and easier to understand when you see it. To be honest, I would not do it like this next year as I needed a ladder to pick the tomatoes at the top and during clean-up I think 5 gallon buckets (with soil) are still too small for big plants like this. Next year I go for the “Kratky method”, no soil so less maintenance and more space for the roots. Just 5 gallon buckets with liquid fertilizer in them.

I bought them on eBay many years ago, I think I saw them not so long ago on Amazon. They are called evacuated solar tubes.

@@marcelthomassen3152 Thank you for your prompt feedback. Yes they are on Amazon ;P

Thanks for your comment. No I did not and yes if I would place the tube square towards the sun the heated area would be bigger thus more heat. But eventually this should be a tube of 1500 mm and placed outside against the wall with a box under it that leads the intake and heated air through the wall into the house. Outside temperature has no influence on the efficiency of the tube as it is vacuum. Maybe the outcome would be a bit less because the sun would be in an angle, in the other way, nothing more simple and cheap like this. One (long) tube would generate a lot of heat if the sun shines. I did tests in the past with 3 tubes (180 mm!) in series but the resistance for the air was too much but if I turned off the blower for only 1 minute (it happened) and turned it on again, all my ABS connections burned…….

@@marcelthomassen3152 Wow, powerfull !!😅 Solar chemney can help for passive aeration also ; )

Hi Jay, thanks for your comment. I think this is an interesting idea but after thinking about it I still would not have tried it. It would make the make the air flow much easier, I will admit that but extracting heat with air is not like a heat pipe giving the heat to water which is much more efficient. So for my (gut) feeling I tried to make the heat-exchange surface (inside vacuum pipe) as big as possible in order to get the most heat out of it, after all, the (super-hot) surface-head of the heat pipe is MUCH smaller than the inside of the vacuum pipe. Not sure if I made my point clear to you.

@@marcelthomassen3152 your point makes sense, the condenser bulb end offers not much total surface area for the air, thanks for sharing that!

You can do that, it is just the filter will get clogged fast and is not easy to clean well.

Hello Roger, thanks for your message. I have taken a peek at your documentation on the Internet but that was just general info, no real details, but as always, much “advice” from others who never done something like this. I will give my 2 cents on 3 subjects. 1. Heat storage I don’t believe in heat storage, been there done all of that. The ONLY good way to use “excessive” heat is the have a dedicated room with a heat pump water heater in it. That water heater will use the warm air in your dedicated room to store warm water for later. The efficiency of such a water pump heater will double or even triple when it can use warm air. All the rest like storage in rocks and wax etc. is just BS, it is outdated. 2. Inner tubes inside the evacuated tubes. The following is the MOST important thing that you need to do correct. The area of the inner tube has to be as close as can be as the same area between the 2 tubes so you have as less resistance as possible. (so NO ½” pipe inside, go with ¾” or calculate it and see what is on the shelve somewhere) The material of the inner tube can be aluminum or stainless as well as long as it is not plastic. I also experimented with galvanized fence poles but they were too big. My spiral is NOT DISTURBING the air, you got that wrong. It guides the air for a longer distance through the tube so it picks up more heat without any resistance. I have checked that with an aerometer. 3. Your output of 1,432 watt is on the low side for 18 tubes, I had more with 3 tubes in series (5 ft long, no spiral inside) but had too much resistance for the air pump. I think your system is better but it makes me wonder if, in a manifold of 18 tubes the air is distributed evenly. Maybe (if you have more tubes) you could make a simple manifold of 5 tubes and measure the output, I bet ya that, per ratio you will come out better. Another advantage would be that, if one air pump breaks down you still get heat from the other manifolds. Hope this helps.

Thanks for the detailed reply Marcel, as usual some thought provoking info in there. When you say no real details, I wonder if you saw there are 11 pages in the thread. Lots of details, diagrams and photos. The forum layout is a bit dodgy and often you have to scroll to the right to see links for the extra pages. Obviously the last few pages have the latest info. And yes, lots of opinions too ... but I value them because it helps in my decision making process and learning about concepts I'm not familiar with. Clearly there are opinions I don't bother with because they're not helpful, but I can tune them out easily enough. 😀 1. Heat storage ... wow, I definitely hadn't thought of that method. Has me wondering about how hard and how expensive that might be to apply here. I am aware of heat pumps of course, but hadn't considered 'helping them along' like you suggest. Great idea. 2. Inner tubes inside the evacuated tubes ... yes, that is something that stood out to me at the beginning ... having an equal area going down the tubes as coming out ... to provide the least air resistance. I spent a long time looking for thin wall tubing of about 32mm ... and with the total length I needed, was going to be expensive. I managed to find some s/h aluminium tubing at a recycling centre and it only cost $2 per length ... though I had to add 400mm to the length of each one to reach further in the evac tubes. Still would be good to find some really thin walled tube, but the cost is going to be pretty high compared to that. Something like curtain rods or tent poles perhaps. "My spiral is NOT DISTURBING the air, you got that wrong." ... ahh, sorry. And yes, I see your point. So I assume it becomes a tradeoff between amount of time air spends in the tube and the outlet temperature ... and an decreased airflow velocity. So hotter air out at a slower rate ... or slightly less temperature at a higher rate. I do recall now where I read about needing to 'disturb' the air in the tubes (was in a research paper) ... but the supposed reason was because the air near the surfaces (where it is hottest) tends to 'stick' to the surfaces and so doesn't transfer the heat that it should. Hence a need to generate some sort of 'disturbace' to break up that hot air so it mixes in the airflow and can be harvested. 3. Your output of 1,432 watt is on the low side for 18 tubes ... I don't really have anything else to compare with so was just happy to see that amount ... though there are plenty of times where it's only 20% of that. I am happy with the airflow ... it's generally at 3.02 meters per second, though high speed is 3.5. On days where there is little sun and little warmth coming from the outlet, I switch it back to half again (1.5 m/s) and that allows the air more time to gain some extra heat. The inline exhaust style fan I am using is only 42 watts on low and 50 watts on high ... so very economical to run compared to a high speed blower fan. I guess I need to work out if getting the air to spend more time in the tubes using a spiral guide like you have demonstrated, will outweigh the extra power needed to push through sufficient air ... or whether an air disturbance type method might achieve the same outcome. As usual, lots of food for thought. Thank you.

@@rogerweichert4672 You have an email address?

Not if you add up the shipping cost.

Hi Roger, thank you for the compliment. When I started solar testing with these tubes (in the very early beginning) I did that actually with water, not air. I used a 6 foot evacuated tube and had a ½” copper pipe inside a ¾” copper pipe so the water travelled 2x the distance inside the evacuated tube. Very good results but at that time I was not able to manage some of the effects that I had to eliminate to improve the test results. For instance, the heat inside the tube is not carried away but stays in the tube, on itself that is a good thing of course as it gets SUPER HOT in the tube, but I had 2 tubes that imploded because I did not braze the copper fittings well and the ABS fittings I used just MELTED. Secondly, I needed to store the heated water and at that time I lived in a condo with only a big balcony while I was only testing to satisfy my curiosity so I abandoned the hole idea. Three years later, when I moved from Quebec to Ontario (I am actually a Dutch guy…) I bought a house with a lot of space and picked up the idea of developing a micro rocket stove to put a (water or air) heat exchanger behind it. I developed a real nice mini stove on pellets, here is the link on RUclips: ruclips.net/video/YLNWsFdi_JY/видео.html This mini stove worked really well and gave the possibility of heating on demand, especially in the evenings when you need the energy. I did not use this stove in my house as such but I made a setup in my spa-room in my back garden to heat up the water in the Jacuzzi which still works very well. I think that home-made solar has had its best time now there are these very efficient heat pump water heaters. These heaters take the warm air in your basement and convert it into warm water in the tank. The warmer your basement, the more efficient these heaters are, up to 3x as efficient with a basement of 28 Celsius instead of 18 Celsius and THAT is where my present testing comes in……In time, I want to replace my electrical water heater with a heat pump water heater, build a dedicated room around it and heat the inside air of the dedicated room with a air-solar collector, probably one of 6 foot long, not the small one I do testing with. Next to that, in this way you use the created energy in different ways, shower, washing, doing dishes and radiant heating to name a few, and also in the evenings as the created energy is stored in the tank, not just one room only when the sun shines during the day. Hopefully I explained it clear enough as English is not my mother tongue. "Not disappointing at all until now", yes you interpreted that wrong. I always set the bar low for myself so any first (most of the times bad) result is a good result and leaves a lot of space for improvement, it keeps me positive and motivated to improve. If I would set a “goal” which is too high, I probably would be disappointed. I am an innovator, I made my money with my ideas in the past and I have learned to live with disappointments or bad ideas, but starting with a low bar always keeps me going. / Cheers

@@marcelthomassen3152 Thanks for the explanation Marcel, it all makes good sense. I have come at this from the point of looking for a passive way to heat our home in winter. We're in Australia and our winters are mild compared to where you are. We currently use a wood heater which is really effective and we love it ... but keeping up the wood supply is hard work. Around here there are often evacuated tubes for sale very cheaply ... and I figure that a line of them into a common manifold, as you have already done ... would be a great way of collecting warmth from our winter sun. The (very) basic experimants I have done have me confident that it is worth pursuing, but it also makes sense to not reinvent the wheel and waste time on experiments that you have already tried and disproven. When I say cheap secondhand tubes, I'm talking about 100+ tubes for $100 ... though these are glass tubes only and do not have the copper heat tubes unfortunately. Of course the questions then are, what is the most efficient way of collecting that heat ... how do you use that heat directly ... and how do you store any excess heat for nighttime use. I've looked at heat pumps, but kinda dismissed them because of the expense ... and also because of the lack of expertise for installing and maintaining them around here. We are in a regional area. But I also see your point where you can then use the stored heat for many things ... not just hot air. I keep looking at heatbanks or thermal mass storage ... but also keep coming back to phase change material (PCM) storage. Again that can be expensive, but being passive it is a once off expense ... and it is similar to a heat pump where you can get a COP of well over 1 if designed correctly. Will be interested to hear of your progress. Cheers, Roger

"or have I interpreted that wrong" , yes wrong. I am what people call an "innovator" , retired now but made my money with my ideas. In the past, when I started to work on an idea I set my goals (too) high and as a result the outcome was always less than I expected. So nowadays I set the bar lower and get better results (most of the times) than expected, that gives me a better feeling and it pushes me to go on.

It is a self adhesive mirror film that I bought on eBay years ago. It reflects 95% of the light.

Thank you sir for the reply

If you look closely to the video you will see that I taped a small computer fan to the elbow that pushes the air into the tube. The copper scrubbers I put between the copper pipe and evacuated tube, NOT in the PVC elbow. The tubes I bought long time ago on eBay but I saw them on Amazon as well. MUCH better would be an evacuated tube with a diameter of 100 mm (4”) and a length of 150 cm (5 ft). They sell them on Alibaba but you need to buy a minimum of 100, I asked them and shipping would be around $500 so not going that route. There are tubes for solar cookers that are 100mm (4”), not long and very expensive for me for testing.

@@marcelthomassen3152 thank you for replying. I live off grid (solar power only) in an earth sheltered dome house that’s well insulated and all south facing windows. It gets very cold outside temps in winter here so I still need some heat source. I have a rocket stove that works great but I am trying to find a way to use the sun for heat instead for when I am not able to collect wood in my older age. Thank you for sharing your ideas it has given me inspiration to find a way that will work for me😊

@@TamiDeeLivingFree I am old too lol.... Here is video of testing my micro pellet stove, I started to work on an alternative rocket stove with eventually a water/heat exchanger above it but too much heat from the rocket stove went away through the chimney so I decided to make something MUCH smaller. This micro stove burns pellets and runs on 12V DC and takes only 14 Watt so it could run on solar but only in daytime of course, for the evenings you can simply use a wall adapter 12V DC. In fact, it uses so little energy that it is not useful to set something up for solar. This little stove runs about 50 - 70 hours on a bag of pellets, depending the feed that I set. Here is the video: ruclips.net/video/YLNWsFdi_JY/видео.html

I hear what you are saying, but this is just a prototype to compare different test, not to be a final product. I am preparing though version 2.0 which will be 150 cm (5') long and a diameter of 100 mm (4") which will be mounted outside and upside down, taking the air through the wall from the inside and release the hot air also through the wall to the inside. Just waiting for the materials I have ordered. Thanks for your comment.

@@marcelthomassen3152 when going from the heater through the wall you may want to build a secondary housing at a larger diameter than your standard output, and seal the housing around the output and pull a vacuum on it to insulate the output on it's way to, and through the wall into the building. might be easier to use more 2" abs cut to match the curve of the elbow and plastic welded to it. plastic welders can be found at harbor freight... don't know why i have not seen them anywhere else.

@@marcelthomassen3152 then again.. you might be trying to take air from inside the room out to the heater and then back so your outer wall would need to be larger yet to accommodate the airflow and a vacuum chamber to insulate it. just some thoughts.. you may have already come up with them.

@@af0ulwind115 Yes, I’ve been there done that. I’ve done MANY tests in the past with 6’ tubes (2 3/8” diameter), I even put 3 tubes in series and got REALLY hot air but far too much resistance for a quiet air pump that does not use a lot of hydro, for that the new 4” tube. All the things you can even come up with I have already done, I know how to execute version 2.0

@@marcelthomassen3152 I hope we get to see v2.0 Thank you for sharing.

The metal shelving is there to avoid the bag resting to the side of the vacuum so the is more bag-surface available for suction.

It is a wire shelve used in closet organizers, they sell them at Home Depot but I assume they have them at Walmart as well. Thrifty stores usually have them as well, that would be the cheapest address I guess.

Search Closetmaid

No idea, I keep the pleated filter in case something happens with the bag. It stays clean though.

@@marcelthomassen3152 Understood. Of course it remaining clean is indication that it isn't doing anything. Just seems that if fabricating a cage for more suction is useful.... that removing that restrictive filter would be an even easier improvement.

@@darelldd My guess is, that the filter has to stay in to keep the bag at a certain shape and maximum volume in order to work well. I mean, if you take the filter out, the bag would become a big balloon and get sucked onto the side of the vac and you get less suction, just my 2 cents.

Look on ebay, just ordered a 10 pack for $20 free shipping. It's for the 3-4½ gallon models but I think they carry all sizes

Hi Thomas, After the video I did some testing with a water heat exchanger but it was all too simplistic, not really worth mentioning. Shortly after that I bought a house to flip and I still need a few months to finish that. So I also did not finish the website with do’s and don’ts. The idea behind this little burner was “heat on demand”, start-up takes only 5 minutes and if I stop the pellet feed but keep the air going, the whole thing stops burning is cooled down within minutes. I made a “mini burner” version, to be able to extract as much heat as possible. I can pump up the heat easily to 500-600 Celsius but I would never be able to extract that heat “in-line”, so most of the heat would be lost going out of the chimney. But you could use this burner very well to heat up a storage vessel with water I guess, it would be very efficient and cheap to use. The burner, what you see is a square 100x100mm profile, 400 mm high with an exchangeable burning insert in it at the bottom. This insert consists of a very small burning chamber, 40x40mm and 45 mm high. The air is fed straight under this burning chamber, goes into the red hot pellets but also comes out just above the flames to create efficient air flow for burning. I can create “blue flames” with this but I would have to higher the feed and air but I would burn my axial exhaust fan with these temperatures, also my wooden frame would start to smoke LOL. The most “tricky” part was the pellet feeder. Pellets are not consistent in size and with this very small dosage (4+ grams/min) it was hard to do. For instance, if I use an average dosage of 6 grams/min, the auger will give about 3 pellets each 15 seconds, sometimes 3 small ones, or sometimes 3-4 larger ones. The burning insert, which is so small, must be able to “coop” with this band-width, it took me a few months of testing to come up with the best auger and insert. There are one or two more videos on RUclips about the start of this burner and while I was developing this burner, look them up. I am not going more in detail here because RUclips is full is “know it all’s” who have done nothing themselves but know everything better and tell me what to do. Once I have more time I could perhaps email you some more info, but it can take a while. Cheers Marcel / Canada

You can view the videos I mentioned earlier if you look up "marcel7254". These were just early stages to get more knowledge about rocket stoves. I went in another direction as it is too hard to get total combustion and they all leave pellets residue, too much hassle and maintenance. In one of the videos I experimented with "splitting" the flame in 4 directions to get better combustion, it looks cool but it was not effective.

I did bend it over the side of my work bench, bit by bit and if too much in a particular area you just bend it back. I kept the radius of the wire shelf a bit bigger to create the air gap.

And your point is?

Hi James, when I use the vacuum on course material, I use one bag around 4-5 times. If I use it on fine dust, I use the bag "only" 2-3 times. I am flipping a house and use 2 vacuums, one for course and one for fine dust.

It is a shelf of a closet system

Lol, after 2 years I am actually using only the SECOND paper bag. I only changed the bag because I the shop-vac was used a lot on drywall dust and I was afraid the bag would not clean very well with the drywall dust in it. During those 2 years the shop-vac always performed well, never got over-heated and the motor NEVER made a sound as if it had to work harder.

I used a small angle grinder.

You could use a Dremel to cut the wire shelf.

Bolt cutters work great

URW. I re-use a bag around 5x, then I put a new one in as there starts to be a lot of fine dust in the paper after 5x usage. One Ridgid bag here in my area (Ontario) cost CAD$ 15.00

Yes, whatever the opinion is about the reusable bag, the cage is a big improvement. I tested it on sucking up piece of concrete, just not falling off. Without the cage I was not able to lift it with normal suction. Bag was 75% full at time of the test. Cheers.