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Mitsubishi PVA air handler

ScottinMA | Posted in Mechanicals on
Hello fine Green Building Advisor folks.  I am new to the heat pump world and I am wondering about the air handler on my new Mitsubishi heat pump.  It is a PUZ hyper heat model with a PVA air handler inside.  I find the the air handler fan is always running, even when there is no call for cool in this case.
 
For example, current indoor temp is 72, and I turn the unit on to cool and set it to 77 (fan set to Auto).  The fan on the air handler will kick on and start moving air.  The outdoor unit doesn’t seem to kick on since there is no call for cool (makes sense), but the indoor fan seems to continuously run and pump air.
 
I’m new to heat pumps, but is this normal?
 
Thanks so much.
 
-Scott in MA

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Replies

  1. Expert Member
    AKOS TOTH | | #1

    That is the default setting.

    You'll have to dig through the manual on the unit, ducted Mitsu units usually have the option to stop the fan once the setpoint is reached. Lot of times this is buried, a call to Mitsubishi might be easier. It will be in the same section where you configure the external static pressure and similar items for the unit.

    Usually you also have to configure the unit to use the temperature on the thermostat instead of the one built into the unit for this to work.

    1. ScottinMA | | #3

      Thanks Akos. That's good to know. I was wondering if something had been installed incorrectly. So if this is an option, and leaving the fan run is the default, should it be left alone? Does the unit run better this way?

      In any event, I went looking for a manual, and came across:

      Application Note: 3048 How to turn off indoor unit fan when set point is met

      Instructions seem simple enough.

      Thanks so much for the help!

      1. Expert Member
        AKOS TOTH | | #4

        If you are using your furnace to filter the house air (allergies) or if your ERV/HRV is tied into your HVAC, you will need to keep the fan on all the time.

        I think the default FAN ON is there so that people know the unit is working when installed. There is very little benefit to running the fan all the time, maybe if you have high ceilings and you need to reduce stratification.

      2. user-7061227 | | #5

        Can you provide a link t the manual please?
        Thanks
        Andy

  2. cldlhd | | #2

    Is that option available on Mitsubishi ductless wall units?

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