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  1. #1

    Hmm wet bulb and dry bulb relativity

    Hi, I recently recieved an hvac jobsite information sheet where you fill out all the db and wb and temps, etc. My question is why is it important to check db and wb before and after indoor coil? I used a digital pyschrometer and it gave me the same db temp from supply and return... what am I not doing?

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,815
    Either the ac is broke or your thermometer is broke if the db is the same.

  3. #3
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,815
    Its important to check db of supply and return to know the delta t (change in temp) and the the wb to know delta h (change in enthalpy) to know how much latent heat you're removing. You also use wb to calculate target superheat for fixed orifice systems. Its easy to diagnose problems when you gather all the facts and have a complete picture of how the system is operating. Superheat, subcooling, outdoor ambient, indoor temp, return air wet bulb, condenser discharge air temp ect ect ect.

  4. #4
    As an addition:
    If the fan was in "on" mode and compressor wasn't running, just cycling the indoor air, you prob would not have seen a diff across the coil.
    A thought.

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