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  1. #1
    Join Date
    Jul 2008
    Location
    Dutchess County, NY
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    152

    2 Stage Heat Pump questions

    I got a 2 stage ICP heat pump...17.5 seer Tempstar... when it was installed they had to add some puron to it. But the compressor is 2 stage and it was charged while running on the 1st stage (low). does it matter which stage the compressor runs while it is being charged?
    also, when the 2nd stage kicks in what happens? does it produce colder air? I know the fan speed is supposed to ramp up on the air handler but does the compressor make the indoor coil colder?
    thanks for any info

  2. #2
    Join Date
    Nov 2005
    Location
    Linn Creek, Mo
    Posts
    399
    Quote Originally Posted by Sonicview View Post
    I got a 2 stage ICP heat pump...17.5 seer Tempstar... when it was installed they had to add some puron to it. But the compressor is 2 stage and it was charged while running on the 1st stage (low). does it matter which stage the compressor runs while it is being charged?
    All 2 stage H/p's should be charged in 2nd stage cooling, from all the 2 stage systems that I have worked on.

    Quote Originally Posted by Sonicview View Post
    also, when the 2nd stage kicks in what happens? does it produce colder air? I know the fan speed is supposed to ramp up on the air handler but does the compressor make the indoor coil colder?
    thanks for any info
    The temp should be about the same in 1st and 2nd stage cooling. The blower speed is matched to the stages to maintain supply temp.

    I am sure there will be some one along soon that can explain it better than I can.

  3. #3
    Join Date
    Jul 2008
    Location
    Denver, CO
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    4,229
    When you are cooling in single stage you are only running a fraction of your rated BTU's, you compressor is not running at full capacity there for you are pumping less refrigerant through your system. When you thermostat reaches 2 degress above the setpoint, then your thermostat calls for you 2nd stage to kick in, causeing your compressor to pump refrigerant at full capacity.
    Last edited by Tiger93rsl; 07-27-2008 at 10:39 AM.

  4. #4
    Join Date
    Jul 2008
    Location
    Dutchess County, NY
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    Quote Originally Posted by Tiger93rsl View Post
    When you are cooling in single stage you are only running a fraction of your rated BTU's, you compressor is not running at full capacity there for you are pumping less refrigerant through your system. When you thermostat reaches 2 degress above the setpoint, then your thermostat calls for you 2nd stage to kick in, causeing your compressor to pump refrigerant at full capacity.
    Ok, so when the compressor pumps at full capacity , does it make the indoor coil colder? is that why the fan speeds up ? to blow the cooler air throughout the house to compensate for the demand for cold air?
    thanks

  5. #5
    Join Date
    Jul 2008
    Location
    Denver, CO
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    4,229
    Quote Originally Posted by Sonicview View Post
    Ok, so when the compressor pumps at full capacity , does it make the indoor coil colder? is that why the fan speeds up ? to blow the cooler air throughout the house to compensate for the demand for cold air?
    thanks
    It increaseas the amount of heat that your evaporator can remove from the air.

    Yes, your fan must speed up when you run at full capacity, inorder to make sure that it boils off all the liquid refregerant in the evaporator. If you pump more refrigerant through the evaporator you must allso inrease the airflow through the evaporator. So that your BTU's vs. airflow is in proportion.

    It does not blow colder air throughout your house, it removes more heat throughout your house.
    Last edited by Tiger93rsl; 07-27-2008 at 01:37 PM.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,935
    It would be possible the air coming out the registers will be colder in second stage. Depending where your duct work is located. (attic)
    2 stage systems should only be charged in second stage.
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