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  1. #1
    Join Date
    Jul 2007
    Posts
    21

    Will fan help circulate hot air?

    Problem: Our old house has an old forced air system that unevenly heats the small rooms on the second floor and we want to try to even it out a bit, particularly as our son's bedroom is about 5-6 degrees colder than the other rooms. Part of the reason for this temperature differential is the northwest exposure of the room.
    Systems: The furnace is a relatively new Trane, 2-stage, variable speed. The only hot air return on the second floor is on the far wall of an outside room. The downstairs has 3 hot air returns on the floor.
    The a/c is located in the attic with runs to each 2nd floor room and 3 runs to the fairly open downstairs. In the upstairs, there is a central ceiling return in the hallway, a return in a room that connects two rooms, and a return in our son's bedroom (the room that is most problematic for heat).

    Possible help: It was suggested to me that running the fan from the a/c unit would help to even out the heat in the house (If it is run continuously on fan, it runs pretty low). Will this help? Is it expensive to run it for much of the day (it's a fairly new, high-efficient Trane)?

    THANKS for your help!!

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,776
    That will probably do more to raise your heating bill, then to even the room temps.

    Run the fan of the furnace.
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  3. #3
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,037
    Air conditioning season is over and now it's time to make sure that all the registers and grills for attic mounted units are closed. The attic that the ductwork that's connected to these registers is very often insulated to a level that is drastically less than what the rest of the attic is.

    It's possible that there are existing ductwork issues that feed the upstairs rooms. Running the furncace fan continuously will help you to get an idea what things might need upgrading. If doing this evens out the temperatures in the home, then ductwork modifications might be in order.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  4. #4
    Join Date
    Jul 2007
    Posts
    21
    firecontrol and beenthere,

    thanks for the replies. the advice to run the a/c fan to help even the heating temperature was from the tech who came to do the annual furnace servicing. I think his idea was that with the high returns on the second floor, that this air would be recirculated. I think that he suggested this option rather than running the furnace fan because of the lack of returns upstairs(again, the furnace is in the basement with the old house ducting and the a/c in the attic with new duct system).
    So, even with only one small return (stuck in the corner of an outside room), running the furnace fan should help?
    If so, do I simply set the thermostat to heat and fan on, and leave it?

    Firecontrol, unfortunately, I don't think that modifying the ductwork is a possibility without ripping out the walls.
    I think what I should have done was to put in separate heating and cooling for each floor. Seemed a bit too expensive at the time, particularly for an 1,700 sq foot house.

  5. #5
    Join Date
    Nov 2008
    Location
    port-land OR
    Posts
    111
    personally if it were me, id run the fan on the furnace for a week or so n see how it "feels". being a newer variable speed it should cost less to run than a normal blower according to the sales jackasses that pitch this stuff to me in supply houses. seems to me a hp is a hp, but they say different. i do know having the air constantly moving helps with multi story homes most of the time, but it depends on the setup. even if there are no returns upstairs the air is still moving. if ur attic ducts arnt insulated like mentioned above then do as he says n dont use them in winter, ur just moving heat to ur attic at that point.

    i say try ur easiest options first, clicking the fan switch is pretty darn easy

  6. #6
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,776
    The techs general thought, would be ok, but you end up heating your attic.
    Do you want to pay to heat your attic?

    The furnace being in the basement is typical. Use its fan. Yes, heat, fan set to "on".
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