Wiring summer switch

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

  1. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    I have a G9T06010UPB13A high efficiency furnace. I would like to wire it for summer switch (I have an options on my thermostat). Problem is there is only 2 wires right now that go to my thermostat. Any idea how I can wire the furnace to use that setting? I can run new wire with ease between furnace and thermostat
    Thanks for any help.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Not sure what you mean by a summer switch?! If you mean you want to force the fan on, if the furnace supports that, you'd need one more wire. While you are doing it, you might as well run a 5-wire cable, then, should you change anything, you'd likely have enough to support it...actually some can use a sixth wire, but most only use 5. Then, you'd be able to add a/c and support multiple stages, if it supports that, as well.
  3. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    Thanks for the response. Yes, I meant I want to force the fan on, since my basement is much cooler than my upstairs. This would equalize temp through the house and in turn cool the top floor a bit since i don't have ac.
    I did find another (red) wire that was hiding in my wall behind the thermostat. I can easily attach it to my thermostat. Unfortunately the other end is not attached to the furnace. I'm not sure where should I attach it to, to make the fan go. Any help would be appreciated.
  4. jimbo

    jimbo Plumber

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    Somewhere inside the furnace, possibly on the back of one of the covers, you might find the wiring diagram for the furnace. That will help.
  5. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    I'll check tonight. I'm sure there is something there just not sure if it will be marked as (connect fan wire here) lol
    I'm fairly handy when it comes to anything, but never messed with furnace before and I don’t want to destroy it by connecting it to the wrong place. (i'm clueless about furnaces) Any generic place it should be in? Like would it be on the motor, or maybe some switch or something. I’m sure they are all different but I’d think they would have similar location for wiring.
    Thanks in advance
  6. DonL

    DonL Jack of all trades Master of one

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    If it has only two wires then most likely the Blower is controlled using a Temperature operated switch in the heat exchanger.

    You could use a relay in parallel with that blower switch, and control it with a air conditioner thermostat.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,332
    Location:
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    Assuming your thermostat has a fan/auto switch, and your furnace has a terminal to control it, generically, it is usually the G or green terminal. Hook that wire up to the G terminal on the thermostat and the other end to the G terminal on the furnace, and it should work. Before you do anything, though, verify by looking at the wiring diagram or call someone familiar with that specific furnace. If you have the owner's manual and/or installation guide, it should show this - figuring it out from the wiring diagram inside the cover can be done, but each company uses their own symbols, and it can be hard to read if you've not worked with them before. Basically, you're applying 28vac to the furnace so it can energize a relay (or other electronic control) to turn the fan on.
  8. PistolPete76

    PistolPete76 New Member

    Messages:
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    Location:
    Ontario
    DSC00139.jpg DSC00141.jpg

    I can't see "G" terminal in the furnace. Any idea by looking at the pics?

    I have a w-r model 50a50-241 control for my furnace. Where would i attach a wire for low speed or high speed? Would it be on cool, heat, park , or park?
    Thanks
    Last edited: Jun 20, 2012
  9. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    Ok I found the G terminal.
    I attached green cable to G terminal in the furnace, and the other end to G terminal on the thermostat
    Here is the pic. Still nothing though. My thermostat says that it is working on cool, but the fan does not turn on in the furnace. I tried on and auto option.
    Any insight?

    Attached Files:

  10. DonL

    DonL Jack of all trades Master of one

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    What is the make and model of your thermostat ?
  11. jimbo

    jimbo Plumber

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    8,997
    Location:
    San Diego
    Does your T-stat have a fan switch...labeled ON-OFF-AUTO ??
  12. DonL

    DonL Jack of all trades Master of one

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    Location:
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    I think that the red wire should be connected to R. Why the black was used instead of red seems incorrect.

    The black may be in the wrong place on the thermostat. That would depend where it connects to the thermostat, and the type of thermostat.

    The thermostat may need a Return connected to C. (another wire if it requires power)

    May be time to get the voltmeter out, and look at the thermostat manual.

    Sounds like it may have On/Auto Fan switch. If not No Go.

    With nothing connected to Y, Then the thermostat should not have a Cool mode.

    Is this unit connected to a Air Conditioner also ?
    Last edited: Jun 21, 2012
  13. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    Thanks for all replies.

    The model of thermostat is noma 303M
    here is the pic for the wiring:
    I had only 2 wires attached (as in 2 wire diagram) black into RH and white into W
    I added green wire to G both in the furnace and in the thermostat.

    I have no AC
    I tried to run the fan on heat (it works with the heat but not without)
    I tried to run on cool (auto and on option) Thermostat kicks in and it shows that it is cooling, but fan in the furnace does not kick in
    Would I need another wire for Y to make it work?

    Thanks

    Attached Files:

  14. DonL

    DonL Jack of all trades Master of one

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    Location:
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    Seems that you could run it on heat and put the temp very low. (So heat is not called for)

    Would that make the fan run ?

    I don't think a connection to Y will help.

    Just connect it for the number of wires you are using.

    3 should work.
    Last edited: Jun 21, 2012
  15. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    I tried that with auto setting, and that didn't work. It only moved the fan when i cranked the heat up (higher than room temp) I never tried with ON all the time (at least that i can remember as i was switching it back and forth). I'll give that a try, though it would be nice to have it to kick in in auto mode, but i'll take what i can get.
    Will let you know tonight

    thanks
  16. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX
    It needs to be ON, Auto will not let the fan only run, the way it is wired.

    If you want the T-Stat to control the blower only when calling for cooling then it will need to be rewired, from the norm.
    Last edited: Jun 21, 2012
  17. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    What would have to be changed for that to work?
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,332
    Location:
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    Do you have the jumpers between the RC and RH as shown in the 3-wire heating diagram?

    When the fan switch is in auto, the furnace or a/c generally control the fan, an only indirectly from the thermostat. On heating, it turns on when the air by the heat exchanger gets warm (on many, but not all). On a/c, it often turns the fan on immediately when it calls for cooling. So, if you tried to fool the furnace into thinking it has an a/c unit attached, and you wanted the thermostat to control the fan being on/off, instead of the G terminal, move it to the Y terminal on both ends, and make sure that the thermostat is in the cooling mode. But, if it is wired per the 3-wire heating diagram (with the jumper), putting the fan switch to ON should turn the fan on ANY time the furnace is powered up. The G wire is an override from the furnace's normal control of the blower. When in AUTO mode, the lead is not used, the blower control is all within the furnace based on the thermostat calling for heat/cold, and other internal conditions.
  19. PistolPete76

    PistolPete76 New Member

    Messages:
    12
    Location:
    Ontario
    Just tried to run the fan only on heat but no go. The fan will not turn. So far only way i got it to work is on auto with heat (like it's always been, but that's only good for winter) I'll try to move the wire to y terminal later on when i have a minute and see what happens.
    BTW yes i do have the jumper

    Thanks a bunch for all your help. will let you know how the Y terminal made out

    After switching the wire to Y terminal..... i got nothing :-( hmmmmm
    Last edited: Jun 21, 2012
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,332
    Location:
    New England
    Your furnace may not support a manual fan on function...not all do. What does the manual say about it? Most modern one do, though.
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