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  1. #1
    Join Date
    Apr 2005
    Kingston Ontario Canada
    This morning I deceided to measure the temperature of the air coming from my heat pump. First of all it's a Carrier 38YZA that uses 410A and a Carrier FV4 air handler. I put a temperature probe in the furthest supply air register away the fan coil. The air temperature coming from the register was 91 dgress F. The outside temperature at the same time was 15.6 F. The question is, am I getting good heat from the heat pump at this outside temperature?
    Thanks is advance for your thoughts.


  2. #2

    Thumbs up

    I think 91 degrees is awesome for a heat pump. How far away is that register from the indoor coil?

  3. #3
    Join Date
    Apr 2005
    Kingston Ontario Canada
    Thanks for the reply r 12sniffer. That supply air register is approximately 45 feet away from the fan coil. When I am doing a test like this should I have been using the furthest register or the closest register to the fan coil?
    After reading your answer, it got me thinking that one of my heat strips might have been on. But I don't think so as I have the aux heat locked out until it gets to 15 F. Then it is staged after that.It didn't indicated on my thermidistat that the aux was on either.


    [Edited by thorton on 12-06-2005 at 10:42 AM]

  4. #4
    Join Date
    Mar 2004
    That's good, but I'm not shocked. With a Carrier variable speed air handler and a thermidistat, the system can slow down the blower speed to keep the discharge air from getting too lukewarm when it's cold out. You don't get more heat that way (actually a tiny bit less) because there's less airflow, but putting the heat in a smaller volume of air sure makes it feel a lot better.

    I can't guarantee that this feature is turned on, but it sounds like you've got the right equipment for it, so it sure wouldn't surprise me if it was. To quote the Thermidistat manual:

    Option 16—Enable Super Comfort Heat Mode
    This option requires prior ON selection of heat pump (DIP switch
    No. 1) and Configuration Option No. 5 (Select Variable-Speed
    Blower). Super Comfort Heat mode is part of the Comfort Heat
    Pump system, which comprises a selected combination of Thermidistat
    Control, variable speed Fan Coil, and 3-stage electric
    heater to provide superior heat pump leaving air temperatures
    under all conditions. This option selection modifies heat pump
    blower and auxiliary heat operation to contribute to comfortable
    leaving air temperature. Specifically, this selection provides:
    • Reduced heat pump airflow for outdoor temperatures between
    12° and 40°F.
    • At least 1 stage of electric heat ON for all heating below 12°F.
    While outdoor air temperature is between 12°F and 40°F, the
    Thermidistat Control removes the G signal during heat pump
    heating. The 40FK, FK4C, or FV4A Variable-Speed Fan Coils
    respond by reducing their airflow in the absence of the G signal,
    raising leaving air temperature. For any heating demand below
    12°F, G and W/W1 are turned ON, assuring at least 1 stage of
    electric heat is on, and also increasing leaving air temperature.
    As part of the Comfort Heat pump system, Configuration Option
    No. 9 (Intelligent Heat Staging) should also be set to ON if the heat
    pump is single stage and a 3-stage heater is present.

  5. #5
    Join Date
    Apr 2005
    Kingston Ontario Canada
    very, very good point wyounger. In previous years ( I have had this system for three years) I did indeed have the "Super Comfort Heat" feature turned on. Apparently, this feature does not need to be used with a 410A heat pump.It does not indicate this in the Thermidistat operating instructions, but in the FV4A Fan coil assembly booklet.It specifically says this under the "Set-up instructions For Warmer Heating Temperatures and Super Humidity Control In Cooling" it says when setting up the Thermidistat "option 16 -on R-22 systems set to ON for warmer heat below 40 F. For Puron applications, set to off After having reviewed my Fan Coil owners maual, I deceided to turn off this feature starting this heating season.I still have option # 5 (Variable Speed Blower" turned on and option # 9 "intellgent Heat Staging" turned on also. But like I said when I started this post I have option # 8 "Auxilary Heat Lockout Setting" turned on also, and I have selected 15 Degrees outdoor temperature before any aux heat is prevented from operating. The only electric strip heat I have coming on is "Defrost Heat Select, option 11, I have selected 2, which has both W1 and W2 turned on. You are also correct that I have the right equipment for all of these features and many more.

    Should I have used the furthest supply air register to measure the heat pump temperature, or the closest one to the Fan Coil?

    Thanks so much for responding, I really appreciated it.


    [Edited by thorton on 12-07-2005 at 04:06 PM]

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