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  1. #14
    Join Date
    Jan 2004
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    Lancaster PA
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    67,880
    Quote Originally Posted by hvacker View Post
    I use an Alnor velometer with a static probe. Because I don't consider the TSP to be as important as actual air flow measurements almost any instrument such as a magnehelic or a manometer would be ok.
    A lot of emphasis is placed on static measurements by the manufacturers of test equipment. Some make it sound like a one tool fits all and this is all you need. I doubt anyone with a T&B cert would agree with this.
    If you don't take a ESP/TESP reading. How do you know how much air the RTU/AH is moving. Not unusual for the supply and return to be moving different amounts of air due to duct leakage.

    ESP/TESP readings will tell how much air the unit is moving. But not how much air is being delivered.
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  2. #15
    Join Date
    Feb 2004
    Location
    New Mexico
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    5,490
    Quote Originally Posted by beenthere View Post
    If you don't take a ESP/TESP reading. How do you know how much air the RTU/AH is moving. Not unusual for the supply and return to be moving different amounts of air due to duct leakage.

    ESP/TESP readings will tell how much air the unit is moving. But not how much air is being delivered.
    For the reasons I listed in post #8 the numbers aren't consistently reliable Which is why the numbers regarding the amount of air being moved aren't reliable.
    Again, these criticisms about static testing reliability in terms of real numbers I didn't make up. They are available in TAB publications. My only interest in pointing out possible misinterpretation of the numbers.
    I include static tests in T&B reports, I just don't give them much weight.
    Any tool is useful as long as you know it's limitations. As a quick method of troubleshooting these tests can have value but keep in mind operating conditions are usually different from design and sometimes by a considerable amount.
    Tracers work both ways.

  3. #16
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    5,490
    Quote Originally Posted by ch4man View Post
    will you please rephase your second sentence. its a little unclear. thank you very much.....

    i am very much interested in air flow measurement and have also seen many inconsistances (sp) reguarding tesp vs capacity checks and also dipswitch settings vs. ecm motors/ cfm
    Sure.
    A lot of emphasis is placed on static measurements by the manufacturers of test equipment. Some make it sound like a one tool fits all and this is all you need. I doubt anyone with a T&B cert would agree with this.
    I've seen advertisements on Youtube showing the methods for using a digital manometer for TESP tests w/o ever mentioning the shortcomings of the data charts and graphs. The fact that some data is interpolated from another fan is a little unsettling if I am relying on my numbers to be accurate.
    It's the problem of comparing laboratory performance with real world numbers. Again, I think these tests are useful within their limitations.
    Tracers work both ways.

  4. #17
    Recently, Ive been learning more about static pressure. I serviced a Goodman gaspac with an external static pressure range between 0.1 to 0.5. Does this represent the total static pressure, or supply only?

  5. #18
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    5,476
    Quote Originally Posted by jrhicks View Post
    I serviced a Goodman gaspac with an external static pressure range between 0.1 to 0.5. Does this represent the total static pressure, or supply only?
    Total.

    One test probe in the supply duct, and one in the return duct, as near to the unit as possible.

    Be sure to read blower performance chart notes for specific unit conditions (i.e.- wet or dry coil, with or without filter act...)
    Instead of learning the tricks of the trade, learn the trade.

  6. #19
    I appreciate it rundawg. According to my total number, Im within specs. My supply was bouncing from .05 to .10 and return from .20 to .25. Is that typical for return to read higher?

  7. #20
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    5,476
    Quote Originally Posted by jrhicks View Post
    I appreciate it rundawg. According to my total number, Im within specs. My supply was bouncing from .05 to .10 and return from .20 to .25. Is that typical for return to read higher?
    I don't think you can call any of it typical, but undersized returns are very common.
    Instead of learning the tricks of the trade, learn the trade.

  8. #21
    I appreciate your feed back.

  9. #22
    I have ran thousands of maintenance calls(tune-ups) and every time I have to check SP to properly fill out my paperwork .50" W.C.. From a practical service standpoint I don't think SP readings have as much influence on my system diagnosis as say a dirty filter. The filter is right in front of you. From the installation standpoint SP is a very valuable tool. But probably not as much as just feeling the air come out of the supply register. Common sense.

  10. #23
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    961
    SP is the last, of a list of items i would check for but, its on the list. can you dig it my brotha!

  11. #24
    I dig it.

  12. #25
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,880
    Quote Originally Posted by bcoolgreg View Post
    I have ran thousands of maintenance calls(tune-ups) and every time I have to check SP to properly fill out my paperwork .50" W.C.. From a practical service standpoint I don't think SP readings have as much influence on my system diagnosis as say a dirty filter. The filter is right in front of you. From the installation standpoint SP is a very valuable tool. But probably not as much as just feeling the air come out of the supply register. Common sense.
    At install stat up. Supply .27", return .39". 4 years later. Supply .17", return .52". Knew where to start looking for the air flow problem.
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  13. #26
    Join Date
    Jan 2011
    Location
    Ottawa, Canada
    Posts
    382
    Quote Originally Posted by beenthere View Post
    At install stat up. Supply .27", return .39". 4 years later. Supply .17", return .52". Knew where to start looking for the air flow problem.
    i am also learning about TESP and ESP so I will ask.... is the problem in the return, ie: a blockage? may be a silly question but will solidify my assumptions.Thanks.

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