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  1. #1
    Join Date
    Oct 2004
    Location
    Annapolis, MD: ragboat capitol of the world
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    358

    Carrier 50TJQ012 heat pump

    can anyone explain to me how the defrost control board works on these? Looks essentially the same as the more recent 50TFQ

    both are a mystery to me
    Sam

    Know-it-all? Nope, not even half!

  2. #2
    Join Date
    Jan 2008
    Location
    Hells Kitchen, Phoenix Arizona
    Posts
    318
    from the 50tfq manual...

    "DEFROST (Sizes 004-007) — As frost builds up on the outdoor
    coil, the coil temperature drops below 28 F. When this
    outdoor-coil temperature drop is sensed by the defrost thermostat
    (DFT) and the defrost timer is at the end of a timed period
    (adjustable at 30, 50, or 90 minutes), the unit operates in a
    defrost cycle controlled by the defrost timer and thermostat.
    During this cycle, the reversing valve solenoid (RVS) is
    energized and the outdoor fan shuts off. The electric heaters (if
    installed) will be energized.
    The unit continues to defrost until the coil temperature as
    measured by DFT reaches 65 F, or the duration of defrost cycle
    completes a 10-minute period.
    At the end of the defrost cycle, the electric heaters (if
    installed) and the reversing valve will be deenergized, and the
    outdoor-fan motor will be energized. The unit will now operate
    in the Heating mode.
    If the thermostat is satisfied during a defrost cycle, the unit
    will continue in the Defrost mode until the time or temperature
    constraints are satisfied.
    DEFROST (Sizes 008-012) — When the temperature of the
    outdoor coil drops below 28 F as sensed by the defrost thermostat
    (DFT2) and the defrost timer is at the end of a timed period
    (adjustable at 30, 50, or 90 minutes), reversing valve solenoids
    (RVS1 and RVS2) are energized and the OFC is deenergized.
    This switches the position of the reversing valves and shuts
    off the outdoor fan. The electric heaters (if installed) will be
    energized.
    The unit continues to defrost until the coil temperature as
    measured by DFT2 reaches 65 F, or the duration of defrost
    cycle completes a 10-minute period.
    During the Defrost mode, if circuit 1 defrosts first, RVS1
    will oscillate between Heating and Cooling modes until the
    Defrost mode is complete.
    At the end of the defrost cycle, the electric heaters (if
    installed) will be deenergized; the reversing valves switch and
    the outdoor-fan motor will be energized. The unit will now
    operate in the Heating mode.
    If the space thermostat is satisfied during a defrost cycle, the
    unit will continue in the Defrost mode until the time or temperature
    constraints are satisfied."


  3. #3
    Join Date
    Oct 2004
    Location
    Annapolis, MD: ragboat capitol of the world
    Posts
    358
    Thanks for taking the time to type all that out. It will be very helpful to me today
    Sam

    Know-it-all? Nope, not even half!

  4. #4
    Join Date
    Jan 2008
    Location
    Hells Kitchen, Phoenix Arizona
    Posts
    318
    Cut/paste FTW!!!!

  5. #5
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,257
    ...and you can get your very own pdf copy by going to the Carrier website and searching for literature under "commercial."
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  6. #6
    Join Date
    Oct 2004
    Location
    Annapolis, MD: ragboat capitol of the world
    Posts
    358
    Quote Originally Posted by timebuilder View Post
    ...and you can get your very own pdf copy by going to the Carrier website and searching for literature under "commercial."
    Tried that and could not get anything to come up even when I shortened it to "50"
    Sam

    Know-it-all? Nope, not even half!

  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,257

  8. #8
    Join Date
    Oct 2004
    Location
    Annapolis, MD: ragboat capitol of the world
    Posts
    358
    Sam

    Know-it-all? Nope, not even half!

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