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  1. #1
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    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
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    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
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    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
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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
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    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
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    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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  7. #7
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    great! thanks for the responses...seems like a new contractor is in order...
    but, what would happen to the compressor if the 2nd stage was turned on when it was charged while it was running in the 1st stage? could damage occur or will it just be insufficiently charged ?

  8. #8
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    Quote Originally Posted by Sonicview View Post
    great! thanks for the responses...seems like a new contractor is in order...
    but, what would happen to the compressor if the 2nd stage was turned on when it was charged while it was running in the 1st stage? could damage occur or will it just be insufficiently charged ?
    Both stages should have been running while it was beeing charged to make sure the system was fully charged. But it would not have damaged your system.
    Last edited by Tiger93rsl; 07-27-2008 at 02:29 PM.

  9. #9
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    It has safeties to protect it.
    Your system could be charged right, under or over charged. No way to know with out checking it in second stage.
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  10. #10
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    I see.... The reason I ask is because the unit has never been put into second stage cooling or heating. the zone board he used is not compatible and will not activate it. When they were here they charged it but it was never in 2nd stage while they were doing it. I was going to attempt to wire it up myself with compatible board but it seems like he has left me with a problem that this DIYer may not be able to perform.... I'll leave it to the pros...
    thanks for your input

  11. #11
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    I thought Goodman/Amana products where to be charged in low capacity. I'll see if I can find some supporting information.

    I know we are talking about Tempstar, but one must assume anything and make blanket statements.
    Beware of advice given by some guy on the Internet.

  12. #12
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    Yes Amana/Goodman products are charged in low capacity.

    I don't know the answer for the Tempstar product line but would like an answer if anyone knows for a fact.
    Beware of advice given by some guy on the Internet.

  13. #13
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    the tempstar installation manual states to charge using the subcooling method and to remove one of the yellow wires from the fan control to activate high speed fan. ( not sure if that is considered the 2nd stage) and to measure the temp and pressure of the liquid line. charge in liquid form based on temp.

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