Wiring summer switch

Discussion in 'HVAC Heating & Cooling' started by PistolPete76, Jun 18, 2012.

  1. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    don't have a manual. it's a 10 year old furnace. It was at my place when i bought it 4 years agon.hmmmm.

    Thanks for all your help.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,134
    Location:
    New England
    Remember, if it is in cool mode, the house has to be hotter than the setting to turn on. It is the opposite for heat.
  3. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,314
    Location:
    Houston, TX
    It looks to me that it is going to require the 4 wire hookup.

    It will not know that the air is not installed and will run the fan trying to coll, then shut off after it reaches the therm cool setting.

    Do you have 4 wires available from the Thermostat to the furnace ? What is red doing ?

    You will need 4 wires if you want it to work the way I understand that you want it.

    I do believe that unit is able.


    Did you switch to the Y terminal on both ends and put it on cool as Jim recommended ?
    Last edited: Jun 22, 2012
  4. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    I only have 3 wires right now. if i manually switch the gass off, the fan will turn on when thermostat is adjusted to heat higher than rm temp. Once on though fan will continue to work even after the temp is adjusted manually to lower heat than rm temp. (strange) Have to shut the breaker off to stop it) This work for aout option. If i set it to "on" possition to run constantly the fan will not turn on when the heat is set to lesser temp thatn air temp in the house.
    There is no red wire. black is hooked up to RH white to W and green to G

    I'm gonna see if i can add another wire to trick it into ac mode without ac. thanks for all your help. Might take me a while to run that wire. It's been busy summer.
    Last edited: Jul 9, 2012
  5. Dana

    Dana In the trades

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    2,915
    Location:
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    Running the fan will somewhat equalize the temps if the basement is fully conditioned with ducts, but it's a pretty inefficient way to achieve any cooling, and in the end could prove counterproductive:

    A 600-1000W air handler is adding 2000-3400BTU/hr to the sensible cooling load- think of it as running a 600-1000W space heater in the house. It's unlikely that even through an uninsulated basement slab that the heat transfer through the slab would keep up with even the air-handler portion of the cooling load. A cheap 500W window-shaker air conditioner would be able to move ~2x that amount of heat OUT of the house rather than injecting heat into the house, and it would use less power.

    If you're looking for the cooling wind chill of breeze on sweaty skin, use a 100W portable fan/ceiling fan, and turn it off when unoccupied. You'll be adding a lot less heat to the house that way.
  6. DonL

    DonL Jack of all trades Master of one

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    Location:
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    If it is a squirrel cage blower then how would it be adding 600-1000W to the cooling load ?

    A 1 horse motor in the air flow may.

    Seems like the most you would have to loose is the Electrical power used by the blower.

    The duct work may add more heat than the gain of moving the cooler air tho.
  7. Dana

    Dana In the trades

    Messages:
    2,915
    Location:
    01609
    I didn't look up the power rating of the air handler on the furnace in question, but typical old school single-speed furnace blowers are in the 600-1000W range. If it's ECM drive it might only be 350W, but the principle is the same:

    All power going into the blower motor eventually shows up as heat inside the building, if the air handler and ducts are all inside of conditioned space. Only a small fraction of that is the direct heating of the motor windings- the bulk of it is in the air resistance at the impellers and ducts, register etc. It's a widely disbursed space heater, but a space heater nonetheless. Energy is neither created or destroyed- 100% of the energy going into the motor ends up somewhere eventually as heat, and all of those "somewheres" are inside the thermal boundary of the house.
  8. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,314
    Location:
    Houston, TX
    Move the (W)hite Wire to Y at the Thermostat


    I thought you said you had a red wire that you found behind the thermostat in your earlier post.

    If you only have 3 wires , and it is working the way you say now, Then you should be able to move 1 wire at the thermostat.

    The wire now connected to "W" should be moved to "Y" on the thermostat, and then it should work to cut the fan on and off in cool mode. (Need to leave the gas turned off).

    Then when it gets cold and you need heat you can move the wire back, and turn the gas back on.

    The long way around but should work. Running 4 wires may cure the swapping of wires, and the need to turn off the Gas.


    Dana is correct that it will add some heat also, But you have to decide if it is worth it. If you have better comfort level, It must be doing some good.
  9. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    Yes i have a red wire behind, but it was not used. I had to extend too for it to reach the furnace. Now it's (green) just to make it more color complicated lol.

    I will try the wire switch. It's not that much work.

    with the heat i see what you guys are saying. When I had it running the other day it actually got warmer than cooler. So at the end i may not even use it, but it was cool to learn something new.

    Once again thanks a bunch for all your help
  10. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,314
    Location:
    Houston, TX
    I know here where I live it will heat the house because all of our venting is in the attic.

    I will use it to heat in the winter and when the sun has the attic temp cooking.

    Not much use for cooling tho, if the sun is getting the attic hot.

    If you swap the wires, then when it starts running all the time, that means you are starting to heat instead of cool, and you should turn it off.

    The wire swap should help some.

    Let us know if you have any luck.
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