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  1. #1
    Join Date
    Mar 2005
    Posts
    18
    first of all thank you to everyone in this forum. we have been happily living with our new furnace and central air system. it sure is nice to come home to a comfortable house. we have a Trane XV90 furnace and Trane XL15i air conditioner.

    we have a situation with our air exchanger. the house has an air exchanger system that is triggered on and off by a mechanical timer. it came with the house, don't know any other specifics about it besides that.

    in the last couple of days, it has been hot that the air conditioner was running when the air exchanger was running at the same time.

    first question, should the air exchanger be running at the same time while the air conditioner is cooling the air? is running both at the same time a good thing or a bad thing?

    what's currently happening is when the air exchanger comes on, it turns off power to the furnace (therefore fan) but not the air conditioner. because the furnace fan wasn't running, the coils froze because the air wasn't moving.

    our new furnace is a 2-stage furnace and we have the fan running all the time. our old one was a single stage furnace and so the fan was only on when it was heating.

    this is our first central air system so this is all new to us. i'm thinking of having the installers come back and "fix" it so that the air exchanger doesn't power off the furnace and therefore turning off the fan.

    hot or cold, the current system means that no heating or cooling is happening when the air exchanger is running. the air exchanger is usually set to run for 5 hours everyday. it's currently disabled until we figure out what's "right".

    does having the indoor air circulating while the air exchanger is running defeat the purpose of the air exchange?

    looking forward to hearing from everyone.

    thanks again.


  2. #2
    Join Date
    Apr 2004
    Posts
    7,680
    I cant speak to the design, but clearly it is miswired (somewhere in the furnace) if it has the ability to shut off the furnace blower without removing the call for cooling at the outdoor unit.

  3. #3
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    If your air exchange system is using the furnace for air distribution in the home it is surely wired wrong. How can you cut off heating and cooling for 5 hrs. at a time. The exchanger should be wired to bring on the furnace fan when it comes on. If you are running a full time fan, then you should disconnect any interlock wiring between the exchanger and furnace. Should be a simple fix.
    "Go big or Go Home"

  4. #4
    Join Date
    Mar 2005
    Posts
    18
    the air exchange system is not using the furnace fan for air distribution. there's a different fan that runs.

    this sounds like the installers mis-wired something because when the air exchange system kicks in, the power to the furnace is cut off. as you suggested, i'll have them look at any interlock wiring between the exchanger and the furnace.

    i say that the there's no cooling or heating for 5 hours because that's how we set the timer to the air exchange. with the power to the furnace being turned off when the air exchange comes on, no furnace fan therefore no heating or cooling going on, right?


  5. #5
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    Where is the air exchanger pulling air from?

    Where is it putting fresh air into?

    I want to say it's wired wrong somewhere.. Get the dealer to come out and fix it before the frozen coil leaks down into the furnace control.

  6. #6
    Join Date
    Mar 2005
    Posts
    18
    the air exchanger is pulling air mainly from our laundry room. the exhaust fan in the room comes on automatically when the air exchanger kicks in.

    it's putting fresh air into the house i think through the registers throughout the house.

    i am only guessing here as i don't remember exactly how the thing is suppose to be. how would i go about finding out how the air exchanger is set up? the house is 13 years old and so is the air exchanger. the furnace and a/c are new this year from the month of March.

  7. #7
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,761
    call installing contractor before compressor gets wiped out by refrigerant flood back. leave fresh air off until rewired.

  8. #8
    Join Date
    Mar 2005
    Posts
    18
    the air exchanger has been off since we've discovered the situation to prevent freezing due to the furnace fan being off.

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