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  1. #1

    Single Stage Heat/Dual Stage Cool

    Hi! Just a quick question. Two years ago I had a single stage/multiple speed 80% furnace installed (Coleman G8C). I am thinking of upgrading the cooling this year. Is it possible to get a 2 stage cooling system to work with this furnace? I know I would at least have to get a 2 stage thermostat. I thought maybe there was a way since the furnace has multiple speeds. Thanks!

  2. #2
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,664
    If by saying multi-speed you mean variable speed, then you should be able to do it. I have a feeling you don't have a variable speed due to it being a single stage furnace. I'm not familiar with Coleman, so who knows for sure.
    I like DIY'ers. They pay better to fix.

  3. #3
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by jclaar View Post
    Hi! Just a quick question. Two years ago I had a single stage/multiple speed 80% furnace installed (Coleman G8C). I am thinking of upgrading the cooling this year. Is it possible to get a 2 stage cooling system to work with this furnace? I know I would at least have to get a 2 stage thermostat. I thought maybe there was a way since the furnace has multiple speeds. Thanks!
    The "multi-speed" refers to the air handler fan motor.

    You can get a 2-stage condenser and a matching indoor coil, but you really need a variable speed air handler motor to get the best efficiency out of that 2-stage condenser. If you don't have a v-s motor, I wouldn't go any higher than a 14 SEER system because you won't obtain the higher SEER rating without a v-s motor.

    Good luck.

  4. #4
    Okay. Thanks for the fast replies!

  5. #5
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,765
    if you wanted to use a 2 stage unit adding a relay to control fan speed would be easy to do.

    would not get the rating of a v drive blower but it would work.

    can't go into details but contractor should know how to do it.


    we had 2 stage units a long time before we had v drive blowers.

  6. #6
    Great! I thought I read somewhere else about relays. Thanks again. Also, are the media filters worth the extra money? (hijacking my own thread!)

  7. #7
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,805
    Yes they are, if the duct work is sized right.

    Your multispeed won't slow down enough to take full advantage of 2 stage cooling.
    It won't have the full ability to remove humidity in first stage cooling.

    How ever.
    You can either have a fan speed control installed, or a VS motor upgrade installed.
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