ita a great idea. never thought of doing. then again most companies want me to hook up thermostat and fire up. If the general wants more they get certified air balancers. I believe to get true external static you need to check the ductwork with o.a. damper sealed. you're just differential of fan and coil. your return can be less because it usually shorter and your probably sucking air in through o.a. damper. if you really want accurate airflow you need pitpot and take 16 to 20 fpm readings, i belive, and average them. i have had problems due to curb construction.
I didn’t have to wait until watching the video to like this. It is like pulling teeth to convince guys to check static pressure. “I turned the fan to high and turned the gas pressure down to 3”wc....” love the static pressure awareness I hope some techs follow your lead!
Static Pressure Nerd I think,,,He try to explain ,,,something,,,!, don’t be hassle,,,,! I hope learn something,,!,,, I always ,,,do, good video man ,,,,
Static pressure is so important! I use static pressure before replacements to see if the system is over sized for the duct work. This way I know if the ducts needs to be addressed at the same time. Its just a good insurance policy. Especially if you don't know the history of the unit. I see undersized returns all the time here in Florida. Regarding this video I don't think having a higher static on the supply is an issue. You should always a rule of thumb have less on your return so the unit has enough air to distribute.
Nice video on a semi-taboo topic for commercial RTU's. For over 30 years York has provided ports on their commercial package units to test ESP. Wished other manufacturers would follow suit. They talk about checking ESP in their installation and service manuals but fall short to tell you how or where. Or to make it convenient enough for people to WANT to do it. Many times, you have to be above the ceiling near the roof line to take the pressures... not very desirable. York has their tables figured out with the ports provided on the unit. If you try to take air samples in the same areas on a Rheem, Carrier or Trane, readings will not be correct because they are not external of the unit. You are better off having long tubing and dropping the static pressure probes in the duct and running the tube outside of the unit to your manometer or magnehelic.
Great Video. Thank You. It might be helpful to others to pay very close attention to where you check the static. Think of probe placement as a flash light (the light see's only what is in front of it) and thus is the same for pressure test location. It will only "see" the pressure that is away from test location. Example: Testing evaporator drop In a vertically positioned gas furnace with an evaporator sitting on the furnace. The test point needs to be between the bottom of the evaporator and above the blower bulkhead. If looking for TESP, the return test point (negative) should be between the filter and blower compartment.
Yes, correct. In most articles it states, "as shipped". So if the init has a heat ex and evap packaged together it's included. If it comes in parts like a resi furnace and AC then it's as you described.
Great video Gary! You are right that we should be getting more TESP reading on package units. We use start up sheets on our new installs, which has a section for TESP. We also have sheets on the service end to verify TESP. I have found that when I enter my static pressure probe, as you did on the supply side, I get a much higher reading. So I have only been inserting the hose enough to stay outside the airstream and get my reading. My readings are usually closer to the designed duct static with our new installs.
I've read an article or two on total pressure measurement and it seems, the most reliable on-site method is small hole drilled in the duct wall and tube pressed against it. From practical perspective, sticking tube in the duct facilitate the measurement. Re. probes used/available: are there error characteristics available for these probes, e.g. error as a function of air speed/pitch?
Thanks for the video 👍. As a new comm hvac guy I was wondering how to measure esp on rtu. The only problem with this approach is that all "experts" that I've listened to say that static pressure should be taken in a straight portion of a duct, away from any bends (due to turbulence). Rtu Manuals also show test points in the ductwork, not unit itself. so i am wondering how much is the difference and can i rely on you readings in measuring airflow 🤔😊
Really nice presentation in probe placement and measuring the Delta P. Do you have any vids on plotting that E.S.P. data + BHP + RPM on the manual provide or designed for this unit? I use those tools to calculate the estimated actual Total Airflow. Thanks in advance.
Thank you Sir for this video. I have question, how can I estimate the avilable static pressure form the tonnage without doing the survey? I have 5 tons and 4 tons existing units. I need to design duct system. Can you help me please? Thanks
I have been having an issue with a Carrier RTU recently. Issue was leading to airflow so I checked ductwork inside the space and checked static pressure of RTU. I did it using a Fieldpiece SDMN6 and I just used a single port to check supply and return individually. RTU is rated for 1 inch W.C. Max external static pressure. My supply was ( .63 in w.c) and my return was (-.37). This added up equals 1 inch correct. You don’t factor in the negative correct? Why isn’t your supply in a negative? I though the suction side or return side of blower motor would be in a negative and the discharge or supply would be positive. Younger technician just trying to learn any input would be appreciated. Thanks.
EXTERNAL static pressure....that's static EXTERNAL, to the rtu...doesn't include the rtu. The reason the manufacturer posts allowable external sp is because they have no control over the conditions that their rtu is installed in. So the ESP is for us to measure and it is much more difficult to obtain a good sp reading on an rtu. What you are describing is total static pressure , TSP, which balancers will record as a means of showing the static pressure that the unit is working under. It is a very good number to have, but it is NOT, external static pressure.
