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Thread: furnace fan to circulate wood heat

  1. #1

    Default furnace fan to circulate wood heat

    Sometimes it would be nice to stir the warm air upstairs from the wood stove and the cool/cold air downstairs.

    I've blocked the return air vents downstairs, turned the fan to "on" at the thermostat, and all I get is low speed which effectively does nothing.

    I have seen thermostats that can periodically run the fan to do what I'm after, but I'm not sure I'd get any different behavior out of a different thermostat.

    I've got a Lennox model G60-UHV(x) (not sure which one, I have that on some paperwork but I don't find that on the furnace itself).

    I would like to be able to run the fan in high from the "on" position in the thermostat.


  2. #2
    Join Date
    Dec 2003
    Welland Ontario


    I can't tell you how but the fan could probably set to run at a higher speed when in fan mode.

  3. #3


    Your stove is on the 2nd floor? That is odd!

  4. #4

    Default yup, upstairs

    We put the stove where we wanted the heat. Its in the kitchen/dining/living room area, with the bedrooms down the hall. Downstairs suffers some but it doesn't take long to warm it up with a run of the furnace when we need to.

    Normally we don't run the furnace at all, between the added expense and trouble to get a flu up from the basement and having to go downstairs and tend to the fire down there when we need the heat upstairs for most of the time it just didn't make sense to try and heat the upstairs by heating the downstairs.

    I've read a lot about where to put the stove, and the house was not made with wood heat in mind which meant there was no good way to set up convection through the house, no central location downstairs with a good route through the house for the flu and all that. Also where the stove is we really like it, in the setting area, with a 15' or so straight flu/chimney that comes out right next to the peak of the house, draws like a champ, and sweeps very easy.

    If I could just get the furnace fan to run at a usable speed without heat/cold it would get air moving in the house now and then and also bring the furnace filter and humidifier into play (currently keep a kettle filled with water on the wood stove for some humidity).

    Anyway, thanks.

  5. #5
    Join Date
    Dec 2003
    Kent, WA


    You'll need someone familiar with your furnace. The fan only settings typically runs the fan at either the heating speed or the cooling speed (heating would be most common, since it is typically slower). Some air handlers have a separate setting for fan only with a jumper or control to the fan speed. This setting is typically the slowest, since quiet air circulation is what most people desire.

    A switch could probably be added to kick the fan to medium or high speed when you want it. A good tech could probably even tie this into a thermostat control.

    My Bryant Evolution (same as Carrier Infinity) air handler and thermostat gives 3 settings for fan (low, medium, high) and this can be set as part of the programmable thermostat settings (so my fan runs all day when I'm home at low, and only when heat or AC is on at night or when I'm away). I also have manual override on the fan and can choose off, low, medium, or high which will last until the next program event in the thermostat over rides it.
    Kent, WA

  6. #6


    So I found the "Installation Instructions".

    Here is what I found for my Lennox G60UHV.


    Indoor Blower Speeds

    - When the thermostat is set to "FAN ON," the indoor blower will run continuously at approximately 38% of the second-stage cooling speed when there is no cooling or heating demand.


    It states that the factory settings of the dip switches for second-stage cooling is in "high speed" and that is indeed the case with my unit.

    There is also a "Blower Speed Adjustment" pair of dip switches which can adjust +-10% or "Normal" which I adjusted to +10% to see whether it is even noticeable, probably put it back to "Normal" unless it proves useful for this application during the winter.

    It looks like this controller (SureLight Two-Stage, Variable Integrated Control Board) has little to offer me in this situation. No way to run the fan on high in "Fan ON" mode through any normal config.

    Thanks everyone, appreciate it.

  7. #7


    I tried running the air handler fan while using my wood stove. It didn't work nearly as well as just one well placed pole fan.

    In my case the problem comes from an unheated basement. I have all the basement duct work wrapped with R13 but the furnace itself isn't insulated. That large thermal mass works well at cooling down the warm air from the wood stove.

  8. #8


    I get the feeling I'm doing my best at trying to warm up the ducts, but not much is left if any by the time it gets out. Why I was wanting to move more air. Downstairs is finished, just need to probably get a source of heat down there, maybe a direct vent pellet/corn stove some day, no way I'm going to sort out getting a flu/chimney 20'+ up, and a pellet/corn stove will be easier to deal with for occasional use, should start/stop a lot easier, who knows.

    Upstairs I have a fan that points from the room the stove is in down the hall towards the bedrooms. Its up high and points down at a slight angle through the warm upper air and you can really tell the difference in the bedrooms. Without it you can stand with one hand on either side of the door up towards the ceiling and really feel how the air isn't migrating.

    I'd love to have transom windows above all the bedroom doors, but there is a stud off-center in the middle of each of them, so I'd have to do more than punch a hole (or two, with a stud in the middle) and frame them in.

    Oh well, I learned something about my furnace I guess.

    Thanks everyone

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