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Separate a/c and furnace

pitt1717pitt1717 NJMember
edited December 2017 in ecobee

So I tried hooking up the ecobee3 lite with no luck
current stat has
r - rc
y -y
g - g

r -r
w - o/b
g -g

both greens in 1 terminal

I did a 1 for 1 to the ecobee except the white I went to w1 instead of o/b as furnace board shows w1. I pig tailed the greens to the g post and connected the b to c on the ecobee to furnace. worked for 1 cycle then stayed on and wouldn't turn off. today I placed a call to ecobee. they had me:
remove the blue from the furnace and attach the blue from the ac.
also did not pig tail the greens. just used the green from the ac. put the green heat off to the side. ran 1 cycle blue the fuse on the board.
ran to the store got some fuses (3amp) put a new one in, same thing. as it is so cold put back the old thermostat and piped in a new fuse, all is working.
what am I doing wrong here?

forgot to mention, there is a white along with the blue on the c/24 term at the furnace. that goes up to a humidifier


  • kevinmcckevinmcc Macomb, ILMember
    edited December 2017

    Pictures of your wiring at both ends and makes and models of the equipment you are connecting the thermostat would be helpful. Include the humidifier and if you are using a humidistat?

  • pitt1717pitt1717 NJMember
    edited December 2017

    thanks for responding. once everyone is up and dressed ill take some pics. really appreciate the help. im usually pretty handy and can't believe I'm getting beat by 6 or 7 wires... grrrrrrrr

    also, when I get the pics whats the best way to upload them?

  • pitt1717pitt1717 NJMember
    edited December 2017

    All pics are up.

    model numbers are in pics........
    both A/C and furnace are carrier.
    humidistat and humidifier are Honeywell.

    fyi, on the ACBoard.jpg, disregard the blue wire as I disconnected it from the thermostat for now. and the black wire on that same board was reconnected to C, its for the leak sensor.

    on the furnace board, the white on the 24/c terminal goes to humidistat (from the way it looks)

    on the thermostat, there are 2 green wires, both going into g.


  • kevinmcckevinmcc Macomb, ILMember

    I would try disconnecting the G wires, and be sure to separate them, and cap each of them with a wire nut.

    See if that corrects your issues.

    I think your issue is two different transforms on two different air handlers. Such a strange setup.

  • so your saying to use neither of the g wires? I never use the fan manually so I guess I could. just would like to understand what else is being taken out of the picture if I don't use these wires. why do you think this would help? (sorry if it reads sarcastic, doesn't mean to be. just asking so maybe I can learn something)

  • kevinmcckevinmcc Macomb, ILMember

    Both air handlers should control the fan for heating and cooling. Since you lite model and won't be using an accessory, fan control is really only useful for the thermostat to call for air circulation without heating or cooling. You really won't lose anything if you do not use fan circulation.

  • one other question. I used the blue wire from the furnace. but calling ecobee they told me to use the one from the a/c unit. does it matter? I ask because working on the furnace is easier (downstairs opposed to attic)

  • kevinmcckevinmcc Macomb, ILMember

    You do want to use C from AC air handler. The Ecobee will want to power the Ecobee with the Rc and C. The Rh and W1 kind of act separately like you would if you had a boiler heat.

  • ok so no g's and common from A/c

    y to y1
    g do not use
    r to Rc
    B to common

    r to Rh
    w to w1
    g do not use

  • kevinmcckevinmcc Macomb, ILMember

    Try that out, see if you have same issues.

  • well I just finished trying that setup. blew the 3amp fuse on the furnace board again. the ecobee is set to hvac, that is the correct setting right? at least that is what ecobee told me although the device itself says that the thermostat is recommended

  • kevinmcckevinmcc Macomb, ILMember

    Yes HVAC control for heat is normal. Try leaving Rh disconnected and see what happens.

    I think you maybe running in to voltage and phase issues with the two air handlers. Only other thing I can suggest is see if you can disconnect the 24vac transformer on both air handlers. Get getting a 24vac transformer that is 60va or larger and try running both air handlers from the same transformer. You would then only need the one R then.

  • SneakXSneakX MontrealMember

    The fuse blowing thing is kinda bugging me...

    With the R and W wires disconnected at the furnace board, could you try to jump R to W directly on the furnace board to see if it activates the furnace without blowing a fuse ? If yes you can be sure it is a power issue, meaning the Ecobee is having trouble at managing two different power sources on both RC and RH. If not, something else on the furnace side is wrong.

  • pitt1717pitt1717 NJMember

    can you elaborate a bit more on the setup? do you want me to put the ecobee back in with the rc, y and blue on the a/c side in their respective places and disconnect the w, rc at the furnace? if I do that how will there be any signal going to the furnace?
    or do you want me to jumper the r and w in my current working setup? just trying to understand before I start taking this apart again

  • pitt1717pitt1717 NJMember

    nm, due to a long night of football I had to take a second read.... I jumped the 2 terminals and furnaced worked without issue

  • SneakXSneakX MontrealMember

    Ok, it really means the Ecobee would need both units to have the same power source. Back to the beginning...

    Do you have a multimeter with you ? With everything connected back on the Ecobee backplane, could you measure the AC voltage between RC and RH, between RC and C and between RH and C ? This could give us some hints about what is going on.

  • pitt1717pitt1717 NJMember

    hi all, didn't forget about this.... ill def try that sneak when I get a chance. just been so cold in jersey that I can't afford to screw around right now and be without heat.
    also, from my last bout with this thing last weekend. what I have found is by utilizing all the wires on the cooling side and just the W wire to heat, AC comes on but heat never comes on.
    I then disconnected all the cooling and just put in the heating side, taking cooling completely off and heat will not come on.
    as I said, ill take a meter reading when the cold lets up, but does it sound like maybe the ecobee is faulty???

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