Static Pressure Testing and Mapping Demonstration 

You're the first person to actually explain what static pressure is clearly. Thank you.

I've been doing research on static pressure to understand it better, and this is the best video I've seen on the subject. Highly recommended to HVAC people.

I paid thousands of dollars to go to college for HVACR in order to become an HVACR Technician, and my instructor didn't teach us any of this. We either learned (almost) everything from an online educational program (Cengage Learning) or our book. Our teacher often took days off in order to go fishing. I'm pissed; I learned more from this guy about static pressure (and other sections of HVACR from other people here on RU-vid) than I have from my 'teacher'. 🤬🤬🤬 Thank you, Corbett. I actually just watched this video about five times back-to-back. After all, repetition is the basis of all teaching. 😏

Such a great video of clearly explaining static Pressure. We get static pressure readings on every call our techs go on. Keep up the great work!

33 year HVAC guy, who started in Air Balance for 3 years. Your videos rock, and you're an effective communicator. I've attended many classes with brilliant instructors who couldn't instruct. That's not you.

Corbett, This is a rare find! A superior instructional tool... Thank you much!

Nice! I'm an HVAC student and its been a while since my first class. This material is refreshing. Thank you.

Well done 👏 The pressure drop of coil + filter called internal static pressure . The pressure drop of the duct called external static ptessure .

Great work Corbett, one simple line from you cleared up my head. Thanks.

My instructor gave us topics to research before discussing it, and static pressure is one of them. This cleared up a WHOLE LOT for me! Great explanation! Thank you!

Thank you, bravo , excellent job at explain in layman's terms so our consumers can get a better understanding of what should be done on every installation. It's too bad the majority of technicians installing furnaces do not even know this, at most they just seen pictures in literature but never had their bosses actually run them through it and explain it to them so it never gets done and the customer usually ends up with an inferior install. Thank you for all your effort and passion to educate people about the subject.

Thank you. Finally a Static Pressure video that was clear and concise. Answered all the questions that i should have already known the answers to.

I've been searching for a good static pressure explanation video all over RU-vid and none of them are as thorough and precise as yours has been! Thanks for taking the time to explain this procedure step by step.

great video lets see more on static pressure

Well explained and after watching several times and mapping my system which is different than most, I finally understand the pressures and meanings. Thanks.

Great video! Thanks for educating! It made all the pieces fall into place! Sometime a video makes sense when the books dont!

This guy does the best Tutorial I've ever experience, and I have been watching him for a good while...

Anyone else notice how nice that install is.

Absolutely the best explanation I've seen on RU-vid!!!

Great breakdown of Total static pressure. Thanks for the video!!

Great presentation. This helped me get more involved in air flow testing a few years ago. Hence to name, static pressure nerd. I would be interested to see the pressure drops in the return drop!

Well done SIMPLE video. We use this in our training (for a few years now) when we are onboarding new team members. Thanks for the content, keep it coming brother.

As a retired service and training manager for a major brand and an instructor of manual J & D, I ground your video to be excellent, correct, and very well explained. Great job! Airflow and air duct testing is so important as many system failures are traceable back to a faulty duct system. A “ tip” if I may. When drilling into a furnace or air handler beware that there’s insulation ( in many cases) that’s only glued on and any excess pressure from the drill may loosen the insulation causing an eventual failure of adhesion allowing the insulation to start flopping around with some ending up on the evaporator coil. Another way, on furnaces, would be to remove the high limit and go in there. You’ll be between heat exchanger cells right above the blower and get a accurate reading too. This way you will not damage the insulation. Just of course be aware that one leg on the limit is hot with 24 volts, so as not to blow the fuse on the board. Real bummer 😖 This video has very valuable information guys, please use it.

You are very good at explaining and your teaching is very straight forward and easy to understand, thank you very much

There are a lot of videos and web sites that address static pressure. This video is the best of all of them.

That is the best explanation of this subject that I have heard. Thank you for sharing this excellent video.

Super clear & enthusiastic presentation!

Great Video. You are a gifted speaker and teacher.

Absolutely fantastic explanation! Love it!

Much better explanations and demonstration for the layman than most other videos 👍😎

Excellent content and delivery! Thanks.

Wow!What a great teacher you are. Thanks.

And I forgot to say this is a very good video! Great job!

Thanks, I learned something and I've been doing a/c for 25 years...

very good descriptions in common language that help visualize airflow...

Thank you for this most informative video. I am NOT hvac saavy,but my understanding of it's basic principles,has now been thoroughly upgraded from OH?,to I understand what your saying. Life is good! Be well,friend.

Thanks for this video! Very informative, especially after my boss asked me what external static pressure is 😁

First: thank you for the descriptive and informative video.it was very helpful. I have been doing hvac for 30 years and believe it or not I never considered evaluating static pressures. UNTIL one day I did a change out and removed a zoned damper system including the bypass per customers request and was unable to get my subcooling or super heat correct. It was a nightmare. I called the manufacturer technician support and discovered just how important static pressure truly is. It's not enough just to replace a system without verifying that the ductwork was seized correctly. Now I ALWAYS check static pressures on every job including surveys for new accounts. Be safe everyone

Great video. Thankfully it confirms they way I test static. That is typically ow I test TESP. One slight difference I usually pullout the high limit switch to get the post-blower pre-coil number.

Couldn’t have explained it any better. Thank you!

What a great video, thank you so much. The furnaces in both of my houses had no ports for measuring?? but they do now.

Awesome! By far the most clear explanation of static pressure I've seen! It's been a while for me and I need to do it next week, so I appreciate the refresher! A few notes: 1. That is a quiet AHU, I couldn't hear it in the video! 2. Don't forget the low limit for TESP, 0.08" WC. I've been finding 0.12" is the bottom on some systems - the second floor doesn't cool for squat below that. 3. The positive/negative thing still messes with me. (I'm a little slow sometimes...) Perhaps talk about the difference or spread between the two? The spread -.38 and +.21 is .59. Like I said, I'm a bit slow sometimes... Thanks again for the refresher, I get to freak out once again while I drill holes in a perfectly good furnace next week!

Very nicely explained. Thanks

You tart how to test that furnace really good and I thank you for that.

Great video, I take it the same location of the measured points applies to package units also, thanks.

Very clear demonstration, thanks for posting. I've just determined that my furnace (which was installed by previous owner in 2012) is staved for return air. I found that the heat limit switch was tripping every time the system was kicked into 2nd stage heat. When I remove the panel before the blower the limit switch doesn't trip -- I posit that this allows enough airflow to keep the furnace in operating temperature range. I think the installers never fully tested their installation and now I have to figure out how to solve this inadequate return issue for them. My furnace installation does not have any of the ports you called out as needed in order to make TESP measurements.

Thanks man for this amazing class it was easy and understandable

Fantastic job. I now know what to look for to resolve my problem.

Great video!!! :) I'm a new tech and this opened up my eyes a lot :)

Very helpful. Thank you!

wow great video. This was broken down perfectly.

Nice video. Very true that most don't check sp. Got a kick out of the 'giant fan' comment! I travelled 9 states for an institutional and industrial sheet metal company living out of a service truck and suitcase. Crane and helicopter picks to get equipment on to rooftops and equipment suites. You could actually crawl into the fans I worked with and pretend you were a gerbil if you were so inclined. Our systems that were designed during the tuberculosis period were set up to bring in 100% outside air, heat it, deliver it to the rooms, and then exhaust it through big vents on the roof. In the 80's and 90's we spent days with saws, Jack hammers, drills, the infamous, back breaking 'wacker', and hammers and chisels opening up primary return air chases, and individual room chases to provide return air - and required smoke and fire dampers. There were variable pitch sheaves and vortex dampers to adjust volume (often upgraded from wooden sheaves and flat belts) Million+ btu burners, oil nozzles (sometimes triplex) that drank gallons per hour, even coal stokers (ever had to clear a coal room to get to an auger's shear pin?), early geo- well water circulated through cooling coils, enormous compressors for DX or chillers, huge pneumatic or motorized outside air, mixing, and exhaust dampers, Chai pull, pneumatic, and now ddc controls, and single draft inducer bearings at power plants that weigh more than an entire residential furnace and dx cooling system combined. Had two boilers in a school in Ashtabula ohio that had come OUT of a great lakes steamer in the 1930's. Had to convert them to gas. The last boiler man in the district that knew anything about coal was retiring-- had that scenario at schools all over as coal was being phased out. Remember back in the 80's when one of our sheet metal guys dropped a tinners hammer from a catwalk from duct big enough to drive through at the Ohio Theater in columbus ohio. Just missed the organ. I was often serenaded by Dennis James on their 'Mighty Morton' while performing pm there (35' × 16' filter area with electronic cells and automatic static pressure controlled feed for oiled prefilter rolls {talk about an itchy job!!}) The low notes on that organ would make your innards quiver like the bass guitarist Chris Squire's low notes in Yes's Starship Trooper!! We subcontracted companies that came in to confirm the balance numbers that our engineers had come up with. Our company had been founded in 1867. After merging with a pipe fitting company it took less than 3 years for the new rape and run business model to run it into the ground. They didn't like that I objected to their business approach. Have worked on that little stuff from time to time-- got cut on one of those itsy bitsy zip screw points or a rough cut sliver of metal just about every time I had to try to squeeze my hands into that stuff or work around that light gauge (aluminum foil!!) duct! Lol. Put some give a damn in your work and you'll build friendships that last a lifetime. Was a great trade.

Thank you for the simple video. Very informative

You got it right! The .59 TESP should and does total your other 4 SP readings. SA duct -.07, Coil - .14, Filter -.19, RA duct -.19 = .59 TESP. As you mentioned, the other readings clearly show where the problem of too high TESP is. Thanks

Greetings Just wanted to let you know that I appreciate the video’s you make. I’m sure you get push back from businesses that, in reality, should be thanking you for the information you provide but instead “they” just want things how “they” want them and not to be checked or questioned. Please don’t get discouraged. Just keep on keeping on. Know that you have thousands of guys that appreciate knowing how things are supposed to be. Hope you and your family are well. Grace and Peace Slick

Great job!! Very well explained.

Love everything you speak about.

Excellent teacher 👌

Excellent presentation on subject.

Thank you for creating this video! very well explained

What an amazing video, so easy to understand Thank you

Great job Corbett! You are extremely articulate and able to convey complicated subject matter in an easily understandable manner. You could easily be a TV personality on one of the DYI channels! I’m assuming the drilled holes should be sealed using metal tape?

Great information, good job!

Great video!

We always did static pressure, temperature rise and gas pressure tests on all of our start ups, then recorded the readings and put them in a customer file. If you don’t do this you are not determining if the furnace is running properly and under design conditions

good question everyone, so if you have a roof top packaged unit and want to calculate its external static pressure, do you consider internal pressure drops due to filters and coil? Or do you only calculate the pressure drop due to duct system?

Thank you for this great video ❤. Very informative

Usually I'll pull the limit if the hole is too big I'll put metal tape to make up the space for the magnetic static probe and of course for accuracy . Not all but alot of times in California at least drilling on the side is a real task sometimes the limit is the only answer . Great video

Great info. Thanks for the vid

Thanks 🙏🏼 for the explanation. Nice 👍

Excellent learning sir, and thank you,

I've learned more and understand more static pressure in this 10 min video then I did in 20 years in the trade lol

Very informative and well explained!

Really great video thank you so much

I tell what man. You're a mentor to industry! Dang ole truth is we're all idiots! What we know we inherited. Inheritance requires discern you know what I'm saying man. Calling out the kind from the swag and tossing the bunk under a bus. There may have been a TESP performed on an AH w/out a hole. Some techs remove the limit switch, and testing from there, but doing this will give you a higher reading because of resistance (top of heat exchanger) I try to replace the filter before I test. 4" media filters w/higher or lower merv values also tweak your #'s. Dang ole beer can cold vets deserve respect, but after 20yrs thinking your right when you were actually wrong. I'd respect the man who pointed out this reality proving to me why I had been mistaken. Corbett I think in the future your name may be as recognized as Bob Vila's was 10yrs ago. So if you become the TV host for this new house? I'm applying for a job!

Best video for furnace system. Would be awesome if you did a video for heat pump systems. Thanks for through easy to understand video.

I really like the way you teach and explain so clear for us to understand. Thanks!

Excellent video

Hey, just a heads up from someone who checks static pressure often on gas furnaces, there is a hole into the heat exchanger available after the blower that the manufacturers make for us, just remove the primary limit switch, I prefer NOT to drill holes into equipment if it is unnecessary.

Thanks so much for your- very interesting -video.

If you study anything from ACCA, you will know now in 2022 with the Air handlers, furnaces and package units, the static pressures can exceed 0.5 without causing any issues. Is it ideal to be 0.5 or below, sure I suppose so. But I have seen systems run just fine at 0.9-1.1 without an issue. Variable speed ECM blowers were practically designed for that. But a properly built system with the right amount of return air, a large filtration system 4-6" filters with good air flow, a good variable speed system properly matched with the ducting design and system functions with be most likely below 0.5 but can safely run much higher. For the homes that are completely finished, and ducting cannot be upgraded, the HVAC system can still be spec'ed properly that could be running 0.5-0.9 without a single hiccup. There are just too many variables to say 0.5 is the maximum these days, but this is a 6-7-year-old video and the 80%-98% units have come a long-ways. This is an outdated video but still has some validity for older systems. Like, don't put in a Filtrete 1900 1" in a single stage 20-year-old 80% system, sure you will have problems. But anything with an ECM blower will run fine but I still don't recommend that ridiculous filter. But also, stop putting on those no MERV rated filters that you can see through that cannot even stop flour. Depending, a MERV 8 is a good average for older systems. If you want to pay a $1 a filter and change it monthly with very little filtration, so be it. It is your stuff, but a MERV 5-6 would be fine for that use. Anyone can add a 5" filtration box to their system and have reduced static pressure and better filtration, no matter what year it was built. Just make sure you have good return air, good intake air and generally you will have a pretty healthy system, if serviced yearly and cleaned properly on your coil, condenser and blower. Maintenance is just like a car, after all, they do cost as much to replace! But these days, you can get some amazing systems for a decent price. I sell my clients the best system possible at the best price. Find a small HVAC company that has good reviews, and you will get better service than some big-name company who advertises on TV or mailers. You get to pay for all their advertising, fancy vans/trucks etc. Make sure they do a full manual J, S and D and get 4-5 quotes and ask neighbors and friends on social media for referrals to friends and family. I promise, if you follow some of these rules, you will have success and be happy. Have a great day!!

Now we're getting somewhere. Excellent explanation. That's the stuff most AC guy's don't want you to know.☺

Thank you for this very interesting and great explanation. Won't be that company ever again!

Thank you for putting so much effort into what is probably the best and most informative RU-vid video of its type. Bravo! And guess what. There's no pre-drilled hole in my system!

great video

wow. this was a very great explanation.

great video..thank you..

Great video.. informative

Great video. Most installers might be aware of the pressure drop from the filter- if that. They don't know about the other factors such as ductwork.

Thanks again great video. This is one of weakness

Awesome job.

Really awesome video

i got a 4ton for 1300sqft thats 350ft per ton in southern Nevada easy 115 degree days, i aim to get 1600cfm and my filter is 20x20x1 side by side for a total of 20x40 filter return. i currently use the honeywell HD merv 11 filters but i think ill start using the 3m 1200 merv 11 because of the more surface area on the filter to help decrease static pressure if that doesnt help ill try to use 4in filter

I’d like to see how to use this static pressure test along with a flow hood to measure duct leakage.

I have been doing this for years in the memphis area, I am not only a contractor, but an Instructor at a tech school as well. I try to teach my students these principles to commission units and use a blower performance chart to set proper airflow for A/C. The sad part is the majority of homes run .8 or higher. Those 1" pleated filters are horrible for static. I recommend nothing less than a 2" pleated for single filters at the furnace base. Jack Rise from ACCA taught a class here years ago and called Memphis the land of no return. He was right! After seeing very nice homes with 2x4x16" wall stacks and builders trying to get 2 tons of return in two cavities! The installers in the area have no clue, the builders want the cheapest, and the homebuyers say look at the granite countertops and saltwater inground pool. Next thing I'm telling them the ductwork was done by a doofus because they aren't comfortable.Keep educating! I just replaced a 7 year old system on a new house because the plenum had a 4"x22" hole in it in the attic where it was never sealed! Keep calling out the shoddy work! It's not opinion if there is verifiable performance! Oh, sometimes I can't drill an old furnace in a closet, I normally take out the limit switch for my probe, not ideal, but works!

I am planning to use the pressure drop across my air filter to determine when the correct time to change it is. I have a set of pitot tube and required hardware to install them. I plan to but 1 on each side of the filter. That said, this mean one pitot tube will be located in the blower assembly of my HVAC system. Based on where I have seen in your video and others, the static pressure should be somewhat constant. Since this is a home unit, I do not expect a large variation in pressure across the duct and plan to use only 2 pitot tubes. With one on each side side of the air filter, located in the center (side-to-side) of the duct and about 6" into the air flow. Other than ensuring I am on the correct side of the blower fan, is the location of the pitot tube in the blower compartment important for measuring the static pressure?

very interesting and clear!

thank you very much excellent video

I agree with so many others on here that this was one of the best, easy to understand explanations and demonstrations for basic testing of static pressure with some great references to industry standard measurements such as drop across filter and A-coil etc. Thanks for sharing! I'm actually trying to determine airflow in CFM for my 3-ton heat pump system to see if it is meeting the required 400cfm per ton which would be a total of 1200cfm to work properly & efficiently. I'm finding that determining airflow accurately without expensive testing equipment can be a very difficult thing. And the results of low cost instruments can vary widely. So, what I might share for those on this elusive hunt, are 2 things: 1 is figuring airflow by using a similar probe but with additional tubing connection (Pitot tube). It works the same but collects 2 measurements simultaneously static and velocity. To get an accurate test a series of holes (travers) are drilled across a section of ductwork at predetermined spacing and a timed and averaging is done and then a bunch of tedious conversion mathematics which seems like a lot of trouble. The alternative using this instrument is a single hole in center and an averaging multiplier of .9 is used to get within +/-5%. Another method listed below blew me away and I'd like to hear comments on this. It utilizes a simple formula using volts, amps draw and temperature rise to determine airflow. I've included a link to the article library.coburns.com/HVACTechTips/Calculating%20CFM%20Coburns.pdf

I am working on a tenant complaint about AC cooling not being good enough. This is for a an upstairs duplex apartment unit. The evap is getting nice and cold-maybe too cold. I think the fan speed for the cool is too low. Right now the cool for the motor is on the BLUE (Med-Low). And the heat is on YELOW (Med-High). I alway heard that the cool speed should generally be faster than the heat speed, so Im going to switch the two so the cool is Med-High and the heat is Med-Low. Will this help solve my cooling issue?