Measuring Static Pressure on an Air Handler for Airflow CFM!
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- Опубликовано: 3 апр 2020
- In this HVAC Training Video, I show how to use a Dual Water Column Manometer to Measure Total External Static Pressure to Set Airflow Speed. I double-check airflow with a Hot Wire In-Duct Anemometer. Supervision is needed by a licensed HVACR Tech while performing tasks as Experience and Apprenticeship garners Wisdom and Safety.
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⚠️ Disclaimer:
Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided. ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
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Thanks a lot Randy! I got your other posts and I appreciate them a lot, thanks!
AC Service Tech LLC - to you and your family, may you have a safe and blessed thanksgiving
I'm about to have a new system installed Tuesday I still have time to change my mind I'm very concerned about the age of my ductwork and the effects it would have with possible leaks on a variable speed motor
Spent $10K at a trade school bakc in 2006 and not 1 instructor is as good as this guy. Amazing explanation skills. Thank you.
@@Fred-zt6gf depends who your teachers are . a degree with on field experience goes a long way
Ain't that some $#!%? 🤔
I went through the same thing; my instructor didn't teach me a damn thing about how to determine CFMs through pressure drops.
You either learned your material online or your book, or you didn't learn anything.
He had his mind set on fishing, and would even take off several days at a time to do so.
@@Fred-zt6gf i agree that experience and knowing what you are doing is important but are you really gonna be on your hands and knees forever? get that experience plus degree then move to a professional setting or something
@@Fred-zt6gf i didnt mean to offend you fred. I'm just saying not everyone is fortunate enough to work in sales or management but an education helps in some aspects to acquire certain jobs but all and all
there is truth behind mine and your statements
True that, I ask my instructor about stuff I learn here and he was clueless with almost 30 years experience. He just taught what industry standards back in days which is not much relevant in todays best practices
Every Saturday morning look forward to the notification I don’t comment a lot but I do watch the videos
Thanks a lot Matt, I always appreciate hearing from you!
If more techs took these readings and verified proper on every startup, the industry would have far less problems. This is the first reading that should be taken, as part of troubleshooting, before any attempted repairs are attempted. Good job.
Wouldn't fix refrigerant problems with all the piece of shit evaporator coils all the manufacturers have. Trane being the worst as far as leaking coils that are only 1 to 5 years old.
Thank you
Bought the books and cards. The books and videos are the equivalent of a distance learning class! This where we are headed now!
As always, you make a very clear and concise explanation of what can be a rather complicated measurement.
As time is always a factor in watching a video, you are the best.
Bart, that is awesome to hear! Thank you!
Just purchased your E-Book last night. Great book and awesome job putting everything into easy to understand terms! Loving it so far!
Thank you very much Yaboy Daniel!!!
Now I understand this Static pressure Clearly.
I have been having difficulty of it in the pass.
Thank You!!!
You have a unique way of explaining things in a way that's very concise and accurate. I'll be purchasing your book.
Thanks a lot Aex and I would be excited to hear what you think of the book after reading it!
I recommend getting the cards to. I use them often.
Excellent content, Craig. Great job at handling those who struggle to grasp your words as well. Keep up the good work!
I always try to be open and we are all in a constant state of learning which includes myself. We can all learn from each other and everyone brings something else to the table for sure, thanks!
Your channel has helped me so much. Doing install right now, and wanting to go to service one day. You have so much useful information. Thanks for the time to make these videos to help the newer guys like myself!
That's awesome! I really appreciate the note! Make sure to check out our website, especially all the articles I wrote and the podcasts, thanks!
@@acservicetechchannel
Really thankful for u videos
Please tell me what’s the link for website and the articles
How's the career going brother
@@leonardlewis5586 Toronto is hot
Dude this video is so helpful. Proper explanation and easy to follow. You the man!
I love how you explained this!
Great explanation. Thanks so much!
Great content. Your videos make me a better tech. This and the heat rise is how I prefer to set my airflow. Thanks for the video.
Thanks a lot Dean Martin!
Nice way to make it easy to tune in proper airflow
Thanks William!
Great Video. Thank you for sharing
Thanks a lot Ze Kenzy!
you are amazing with this videos
Beautiful teaching ❤❤❤ USA
Not even i listen but i keep your lessons in my memory .AWESOME . GOD SPEED✟✟✟
Wow, thank you
nice explanation and demonstration
Great video great explanation , thank you
Thank you for your support!
Great Video, Thank You. I find it interesting that while manufactures require a recorded TESP for proper commissioning, they don't design in probe holes for that testing. I have always hated drilling holes in new cabinets..
Yeah it is odd but in the case of furnaces, some time we cut the side of the furnace out anyway so it would depend on where the duct connects at but the supply should have one. There really is no reason not to other than they don't want a plug in their unit from them!
Ray here is a beast
Nice job and video
Great job
Great content with good information.
Glad you think so!
@@acservicetechchannel sent an e-mail to you. Please check.
🤘⚡️🤘. Great info as always
Thanks a lot Dave! I appreciate it!!!
Well done from beginning to end...thorough explanation not omitting any critical info,
👏🏽 👏🏽 thank you 🫡
Hello and thank you for all your teachings . I just bought your book, workbook and cards . It’s like treasure box of information and I HIGHLY recommend all of them to anyone who is serious about mastering HVAC. I Have a question regarding airflow and static pressure. When you took your measurement you inserted the probe into the return duct. I live in Miami and here HVAC systems do not have a return duct. Instead the air handler sits in a closet with louvered doors. The return on the air handler is just open to the hallway outside the bedrooms . This is the case in all houses here . Where do I place the probe to measure static pressure ?
Thanks for video it is thorough, well done and very informative. I have an older carrier 58mca-060-16110 furnace. I have a manometer to take static pressures but don't have airflow charts to calculate CFM. Other than expensive equipment is there any other way to go about it or can you point me to a source for tables? Thanks
Great video, thank you!! My furnace did not come with a filter. I have filters at the return grills. However, my ESP table assume a filter is at the unit. How would I handle this?
Thanks
Thanks Shawn!
Helpful video, thanks. One thing that I find confusing is the use of the phrase “static pressure” (i.e., singular versus plural “pressures”). This description suggests that there is a single pressure measurement in the system. It seems that a better way to discuss this subject would be to describe the system as a series-connected set of components each having a pressure drop across it (i.e., pressure DIFFERENCES). This approach is akin to describing voltage drops across a set of series-connected electrical components.
If the filter is new when i run my test, then I'm inclined to overshoot the chart slightly to account for filter degradation. Maybe they accounted for that already. Who knows. Some systems are very sensitive to filter type and require a poly fiber filter. (electric furnaces are famous for this)
I'm wondering if this instrument doesn't measure Total pressure (static + dynamic)? If you measure the static pressure, you would measure at a point where there is zero velocity (like the wall of the duct). A pitot tube measures total - static pressure, giving dynamic pressure that can be used to convert to velocity.
Nice share sir
Thanks🙏
Thanks a lot Trick!
Unless you in Florida, Georgia, SC, NC, better off with 350 cfm per ton for better dehumidification.
great video. question about your measuring device.
isn't that a pitot tube? from what I know, the hole at the tip measures the stagnation pressure while the holes on the side measures the static pressure? but both are connected to one pipe that goes to the reader. is that why you only mention static pressure and not stagnation pressure?
This video covers the static pressure per a blower motor that can be changed per dip switches or connector position. What about a Variable Speed Blower? Does the thermistor that is built into the motor module control the speed of the blower motor? In other words thermistors have value, so can the different value thermistors change the static pressure air flow? I have a Nordine made Frigidaire two stage gas fired furnace. It's a down draft unit because we are on a crawl space where the supply ducts are located. Last year the blower would not run. Upon inspection, I found that the motor windings were fine, but the thermistor in the motor module was cracked. I read where this is a problem others have had. The part number on the thermistor was not available per the electronic parts supplier. I found someone who had cross referenced the part with a number that was available. I got one and installed it, but I think the blower runs at a different speed now. I suspect our April air filter was dirty which blocked or reduced the air flow over the thermistor. This reduced the air flow which caused the heat to build up inside the supply plenum. The build up of heat cracked the thermistor. Would that be a possible cause of the thermistor failure? Thanks for the great video on understanding static pressures per the blower motor speed settings. Sizing the system per the home is so very important. We used the Manual D program to help size our furnace and new ductwork. I think it helped a great deal.
Great video. If you have an open return with no duct work to the return side of the AHU how would you check static pressure? Thanks
What kind of readings are you getting on a typical gas furnace with an AC coil for static readings in the field? It seems awful hard to obtain a 0.5 reading. Just the static drop from a coil and filter can use up 0.5. Just tested my furnace and it was reading 1.0 in WC. My 1 inch filter has got to go that alone is a 0.3 drop and I know my duct is undersized for supply and I do not have enough return air either.
That AH install is so clean!
On the supply - are you measuring under the coil, or over? Does that depend on heating or cooling mode static checks (furnace vs. AC).
Quick question. What if there is 2 returns, one on each side. Would you add all 3 values or average the 2 returns and then add that with the supply?
Very helpful video,
Sir, how to charge split system in low ambient temp and how many ways of charging refrigerant in low ambient
Here is a video on low ambient charging thanks! ruclips.net/video/OmQQcjmNLgw/видео.html
Great video as usual. Where can you get the manufactures airflow data info from if its not available the location where you're working?
When checking static pressure should the blower be on the highest speed?
Thx for the vid. Tell me if im wrong but im not totally agree with ur explanation here. So of course we have to measure the SP as close as to the air handler because in this case if we measure before that 90 degree elbow we leave out a whole lot of duct. So its just simply said we have to choose a measure point (not interfere by turbulence) so that we can account for the total length of the duct system. The negative and positive SP here just mean the return and supply air act on the manometer in the opposite direction doesn’t mean it a negative number. So the total SP is total return SP plus total supply SP. The TESP of a particular duct system doesn’t change unless we shorten or lengthen the duct. So if we increase the blower speed on the same duct system we got more velocity pressure but the TESP doesn’t change so no we don’t have to measure the SP again. Lastly to get the right air velocity of the system better do a traverse method because the blower wheel can be dirty over time and dont blow out the same amount of air as spec. Im still learning so hope u can point out where im wrong.
Quang I am right there with you on the measurement location, you must be as close to the system as possible and before any changes in the duct occur. Also on the - and + static pressure readings, I may not have explained that as thoroughly as possible. I was just wanting them to not subtract one from the other. The simplest way to explain it would be to just drop the negative sign. I added another negative to change it to positive in the mathematical formula but didn't mention the static pressure is just a value not necessarily a negative one. That is just how we read it on the manometer. In reference to the last thing though, static pressure does increase if you increase the velocity of the air. You are trying to force more air through the same size opening. Static will increase. You can do some tests on the next system you are working on but that is what happens. Thanks!
I do agree that other methods such as temp rise, traverse, or flow capture hood will be more precise and can be used for service work on an existing system. Often times, this method is just used as a quick setup for the initial installation. Its just one of many methods, thanks!
AC Service Tech LLC thanks seem logical as newton law apply when you said more air more SP force. Would you explain why manufacture list ONE (1) SP for several blower speed which produce several different cfm. Thank you very much
AC Service Tech LLC yes no matter return or supply the motor still has to do the work for that SP present in the system. So the longer the return duct the bigger the return SP in the pulling direction which will exert amp draw on the blower motor. So likewise on the supply side. Thank you very much for ur reply.
@@hangngoaigiare It's just a chart, it has 3 values. You measure any two and you can get the 3rd one from the chart. If you measured LOW speed and .3 static then your CFM is 660 or so. In fact this is being confirmed at the end of the video when he used the other meter to measure CFM directly. It measured 682CFM so based on the chart you can find the SP easily as 682CFM on LOW settings will give you .3.
I was looking at an IOM for an Amana. It gave the static pressure reading not including the coil. Weird.
If you are in a building with fire dampers sometime they will drop particularly around the kitchen area.
Has anyone here done ducted mini splits? I was wondering how the automatic fans maintain the static pressure on a small trunk supply setup
Does the book also covers electric low voltage troubleshooting?
Where do you stick the probe if your filter is not in the duct right before the air handler such as a ceiling grill with a filter? Do you just stick it up near the filter in open air?
What co2 should I buy for wrk
Where would you get the manufacturers thing at to check the static pressure?
Is any way i can buy the books for iPhone download?
Why do we need to shut the condenser off and have it on cooling to set the static ?
Should the probe be before or after the filter?
Ordered manometer going to test today…but my old trane air handler doesn’t have data available…any rule of thumb with no data and a 2.5 ton psc motor. Thanks
I had a guy say my static pressure was 0.59
I think he pushed a hole through the supply duct? Is that high? If it is high does it always mean my ducts are leaking?
Does a air handler box have negative pressure with access door in place?
Where do the probes go exactly ? Right after the blower ? Someone plz explain
The HvacKing boys
Thanks Freddy!
Is the system running in this video?
So when you have insulated ductwork do you cover that hole with a plug afterwards? I guess you need a insulation plug or flap to get access to the duct?
Air balancers use 3/8 red cap plugs to seal the holes. Sometimes there is a whole line of holes if the duct need to be traversed for velocity readings, which are used to determine airflow precisely.
So how do I control the blower speed?
Hey, Just a Noob here. Since you're talking about cfm needed for cooling shouldn't you refer to the wet coil sheet? 6:00
Hello sir. Is there a generic or common PSC motor air performance table one can use if manufacturer data is not readily available.
Each performance table is different so it's nice to have a hot wire anemometer as well thanks
If I had .72 and .26 I would add these together?
As far as I understand it, you mixed two approaches:
1. original, according to manual, you should measure static pressures using straight probe with opening perpendicular to airstream, air velocity does not influence measurement/value, probe should be placed as indicated in the manual,
2. alternative, using Pitot tube directed towards the velocity vector or air, you measure (differential guage) total pressure - static pressure = dynamic pressure, convert to speed, measure CFM using proper formula taking into account velocity profile (difficult, time consuming, possibly lower confidence level.
Please kindly correct me if I'm mistaken.
Luzt, thanks for your comment! This was measuring static pressure and comparing the TESP otherwise known as the ESP to the manufacturers blower data. I used a static pressure tip, not a Pitot tube. This is one of the same methods we use for setting air speed in a furnace. We can also use many other methods like temp rise, in duct hot wire anemometer, rotating vane anemometer, and flow capture hood.
A Pitot tube is used to perform a multi-point traverse. This will measure total pressure and static pressure to show velocity and you must do that in multiple points in a straight section of duct to calculate cfm for the duct.
What I showed was just with a standard static pressure tip, not a pitot tube and I was measuring static pressure only and in only one location. Once I got my return and supply static pressure right outside of the cabinet (external), I added those static pressure readings together to get the TESP otherwise known as ESP. Once again, this is only a static pressure reading. The manufacturer supplies a chart that shows what the cfm will be at certain static pressures and the blower speed selected. The Pitot tube traverse method does not need any manufacturer data and is taken in a straight long section of trunk duct.
So anyway, I have been getting a lot of questions on measuring airflow and this is just one out of many ways to do it. Static pressure is also very useful when trying to determine your low airflow problem such as a clogged evap coil. Thanks Luzt!
@@acservicetechchannel Thank you for your very long answer. Back to my main point - you mentioned 'directing the probe towards the stream of air". If the opening is at the tip of your proble you measure total pressure, not static pressure. Please kindly clarify only this single point.
Yes you are correct if there was a hole in the very end. However, this tip is a static pressure tip so there are 4 holes about 1 inch away from the end of the tip. There is no hole at the very end to measure total pressure so the measurement holes are perpendicular to the air stream. If you can zoom in on the video, you should be able to see the little holes when I hold the tip because this is 4k video.
@@Luzt. A few of us here waiting for your apology. A very long answer is not required.
@@acservicetechchannel OK. Thank you for the clarification. The whole issue arose due to my not being aware there exist L-shaped probes for static pressure only. With that, my point makes no sense.
Still, the whole idea of using the table is based on a close reconstruction of factory set-up. If it were me I'd assume that most technicians do not have this kind of proble and used simple measurement of static pressure one the plane of the wall while making the table.
Can you recommend a cheap good manometer for a non-, professional home owner That just wants to measure static pressure? THANKS!!
Manometer, RISEPRO Digital Air Pressure Meter and Differential Pressure Gauge HVAC Gas Pressure Tester www.amazon.com/dp/B01680C4C2/ref=cm_sw_r_cp_api_glt_fabc_5ZQST3W4B21SPVC669PC
Question please >. I thought static pressure was determined by duct design, how did the static pressure increase from .3 to .4 just because you increased fan speed? THANKS, great video!!
not an expert on airflow but faster blower maybe moving more air.
@@caru3257 ya i forgot about the system pressure curve
Very informative.
Glad it was helpful!
@@acservicetechchannel i purchased your book before the quick reference cards, will be buying those soon
Hi Hello sir. Thanks for the explanation. but I'm a bit confused, so suppose if I wanna start to design a fan from zero. the main parameters for this are the air flow, static pressure (pressure rise), and the fan speed (rpm). How to determine the static pressure ? can we put it as much as we want or is there any basic calculation to wisely select the proper SP for the design parameters ?. In my case, I'm about to use the fan to cool down some electrical objects (generator windings). pls help me.
I'm interested in AC techs response but I think this video is for ducted A/C systems so in your case if you are just using a blower housing to blow on a motor or generator you might use the amp draw to determine the limits. Whereas static pressure is measured inside ductwork. The more you constrict the air flow the lower the amp draw of a "typical" blower motor (a paddle type fan works differently) . If you have to LITTLE restriction of the air flow on a blower the amp draw may cause the motor to overheat. I use a blower (out of a 120volt furnace) mounted on a plywood panel to blow air out of a window of my house when outdoor temp. is moderate and I put a 3 speed switch on it. I also use cardboard to block some flow to reduce the amp draw and also raise the static pressure and reduces the cfm. I never use the high speed on the blower motor with no restriction of air flow I believe that would overheat the motor.
If you are using a ducted air handler the install manual gives the "standard" external static usually .5 sp, which I would read as this air handler will provide this amount of air (cfm) at this amount of external static pressure (resistance) so as you increase the amount of resistance to flow by adding ductwork, filters and grilles you are raising the total static pressure and lowering the amount of cfm.
It is pressure difference between return side and the supply side
You are adjusting CFM for cooling mode , what I heating mode , you don't mention?
In this case, the unit is a heat pump with a psc motor so the blower speed would be the same for heating with the heat pump, thanks!
@@acservicetechchannel thank you for clarification!
Immigration Freedom cooling cfm take into account the sensible and latent heat so per manufacturing evaporator coil for cfm. On the heating side per NCI 100 cfm per 10k btu for natural draft appliance with 75 degree temp rise. 130 cfm per 10k btu for induce draft appliance with 62 degree temp rise and 150 cfm per 10k btu for condensing appliance with 60 degree temp rise.
Where did you get that adapter for the monometer hose?
Amazon, tru tech tools, etc. They're about 29.99 a piece.
I rarely see the airflow data sheet. where should i find that? just look at the manufacturers website and dig?
good question; would like to know the answer as well
In the IOM
Isn't that technically a pitot tube, not static pressure? Seems like 'static' pressure should be measured right at the hole without pointed into the flow.
How do I get your book?
You can purchase that through amazon at www.amazon.com/shop/acservicetech or through our website at www.acservicetech.com/ac-book and we offer better pricing through our website than on amazon because of amazon's referral fees, thanks!
AC Service Tech LLC thank you !
👍
1 inches water column = 249 Pa, for the enlightened people.
The HVAC videos do not discuss the increase in Electric Consumption from High Static conditions.
Over the life of a Furnace, or Air Handler, the waste in power is Staggering, all paid for by the unsuspecting home owner.
Ex: (At 1 amp per 0.1 inch (my furnace/AC is .2 over)=0.16KWH/hr., 1,250hrs/year, 25 Years, $.185/KWH gives
$950 wasted over the life of the unit.)
Im afraid this that chart & how it was explained, left me confused then again im high🐾🍀
I have always been taught that static pressure in the pressure on the duct, not the airflow. Your probes should not be in the airstream but where the air is "static" as in not moving like near the bottom of that return box ant the top of the plenum on the other side of the duct.
Matt, so we really need to be careful where the static pressure tips are placed when taking measurements. You want to be in the middle of the air stream but the holes are measuring perpendicular to the air stream. Because of this, you don't want to take a measurement where you don't know where the air flow is moving or is turbulent or you will accidentally be measuring some of the total pressure instead of static pressure. For instance, if I were to take a measurement toward the top of this plenum in the supply, my measurement would no longer be static pressure and will be higher because I will actually have the air entering directly into the holes on the side of the tip instead of measuring the static pressure in the middle of the air stream. This is because the air is turbulent because the air just hit the end cap. Likewise, if I were to take a measurement in the bottom of the return, the measurement will not be the same as in the middle of the air stream. It all has to do with where your supply trucks are connected to your plenum and this is why its safest to take the measurement as close to the air handler as possible in the least turbulent air stream. I know it sounds odd but all I can tell you is to do some experimentation with some manometers that you trust positioned in different spots in the plenums and you will visually see your measurements change depending on where you are testing at in the plenum. Thanks and great question!
@@acservicetechchannel it wasn't a question I teach HVAC I have done extensive testing and consulted with experts I was trying to educate you if you don't agree do some more research on the subject before making RUclips videos please.
Hey Matt, static pressure readings are take with either 90 degree tips with the holes in the tip after the bend or just by using a straight tip into the side of the duct. Yes static pressure is exerted on all sides of the duct but you have to keep in mind about the total pressure and trying not to accidentally measure that when trying to measure static pressure. The point is to not put the opening of the tip directly into the air stream or where the air is turbulent. Near the end of the supply plenum, if you took your measurement there, you would get an incorrect reading with your tip. It will be much higher there. When you use a 90 degree tip like I used in the video, the point is to have the tip pointed in the air stream so that you don't accidentally measure total pressure instead of static pressure. That is the only reason that you would be concerned with the direction of air flow or the tip position. If I were using a straight tip then I wouldn't have mentioned about the direction of the airflow and pointing the end of the tip in the direction of the airflow. We use this same 90 degree tip between the furnace and the evap and right between the blower and the filter. However, a straight tip like you are mentioning can just be used there as well to keep your measurement closer to the edge of the box.
@@acservicetechchannel I'm not sure you are understanding I haven't used a straight tip I use the same Feildpeice tool and probes you are in the video I have learn for experts in the field and the manufacturers who test the equipment. I have tested this on multiple gas furnaces and air handlers.
@@mattkime7615 you don't get paid to teach, I hope
File this under "Things that don't matter"
Not a very good instruction vid for the layman , need to explain the names of the components and abbreviations mean nothing to a layman 👎