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  1. #1
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78

    2 stage furnace 1 stage AC?

    If I get my furnace upgraded to a 2 stage unit, will it harm my 1 stage condenser? I'm just wondering with the lower (1st) stage there may not be enough airflow across the Acoil. Is it possible that it would freeze the coil before the 2nd stage was called for?

    The current AC condenser is a nordyne 2.5t R22 unit (about 15yrs old)

  2. #2
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062
    Quote Originally Posted by rebelranger View Post
    If I get my furnace upgraded to a 2 stage unit, will it harm my 1 stage condenser? I'm just wondering with the lower (1st) stage there may not be enough airflow across the Acoil. Is it possible that it would freeze the coil before the 2nd stage was called for?

    The current AC condenser is a nordyne 2.5t R22 unit (about 15yrs old)
    No. You will have three levels of fan speed chosen by the control board.

    Highest will be cooling speed,medium will be high heat, and low will be low heat.

  3. #3
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    No. THe furnace operation and cooling operatiosn are seperate on the furnace control board. Cooling airflows and heating airflows are seperate dip switches or taps/contactors on the control board.

    IF you go with a vairable speed blower, it's just a simple dipswitch setting.

    The most common problem is often that the blwoer speed is set too high, and.or hte ductwork is undersized or AC is oversized or a combination of the above.


    ...I guess i was a little slow to type it out.

  4. #4
    Join Date
    Aug 2011
    Location
    Kansas City
    Posts
    78
    Thanks guy, I did some more searching and find this info on here too. I forgot about the 2stage furnace being VS so the control board will ramp up and down as necessary.

  5. #5
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062
    Quote Originally Posted by rebelranger View Post
    Thanks guy, I did some more searching and find this info on here too. I forgot about the 2stage furnace being VS so the control board will ramp up and down as necessary.
    Even if it was not VS the control board would still control Y, W1,and W2 by powering 24 volts through the fan relay for the different speeds needed.

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