Air temp delta / amps pulled

Discussion in 'General Discussions' started by RonL, Feb 18, 2023.

  1. RonL

    RonL Member

    As an average, how much delta do you have between incomming air and what you get at the registers?. And if you ever measured you anemometer speed. (I know that's relative to your duct and register size), but just for a comparison.
    I just replaced my old r22 freon hp with whatever it is now, and I'm seeing a difference. I did upgrade from a 31 to a 36 btu so I expected more volume, but not this much of a temp delta. My numbers are: incomming air is 68, and register air is 85. My old setup was 68/95. I'm getting more volume so it should compensate ..old registers average about 500 where new is 700. (Using anemometer)
    Cost of running... old unit pulled 10 amps, this one is actually a bit less at 9.
    Bigger / lower delta, but cheaper to run. As close as I can tell my incomming water temp is 65 outgoing is 57. (Not sure why my incomming well water is 65, it should be 59.. (at least that's what I measure with a meat thermometer at the kitchen tap ) I'm using an infrared thermometer (like they use on your head at the dr... who nows how accurate, but the delta should be the same) to get my Temps at the hp.
  2. SShaw

    SShaw Active Member Forum Leader

    Typical air delta-t is approximately 25 degrees, but it varies with airflow and EWT. That's across the air coil, not at the registers. If your EWT is 60-65 the delta-t should be higher, more like 35 degrees. If your system is set up to push more than the recommended airflow, the delta-t will be lower.

    Look at the specification documents for your heat pump. The documents should show the expected parameters.

    Infrared thermometers are not accurate for reading off reflective surfaces, such as metal ductwork or pipes. The thermometer will read heat from the surrounding objects reflected off the metal.
  3. RonL

    RonL Member

    The only specs I have or can find are attached. Not sure if it actually tells what your asking.

    Attached Files:

  4. SShaw

    SShaw Active Member Forum Leader

    That's sparse documentation. Maybe Miami Heat Pump doesn't provide data on leaving air temperature.

    If you want to verify your system is working properly you can measure the power consumption, flow and delta-t on the water side, calculate the heat of extraction and heating capacity, then check it against the specs.

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