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Yet another nest/ecobee question

LeSer Member Posts: 19
Yet another how to wire up nest/ecobee question. Basically both nest and ecobee doesn't power on. Nest is 3, i took from my house to tried out. Ecobee 4 is new, got it onsale during BF. This was a house converted from oil to gas. Was on nest 2, nest 2 worked with the R & W wiring. But after conversion, it doesn't work anymore. Any tips ? Thanks..

The boiler is weil mclain peg/eg-50. First pic is existing wiring to simple thermostat , just R & W.
R at thermostat goes to Y in the schematics
W at thermostat goes to W in the schematics
C goes to C in diagram - I added.


  • ratio
    ratio Member Posts: 2,924
    Are you sure about the 'W' terminal? The schematic show the stat going between the 'Y' and the 'G' terminal.
  • LeSer
    LeSer Member Posts: 19
    Yup.. that block is upside down and Y goes to the red wire.. dunno why, it was setup that way..
  • LeSer
    LeSer Member Posts: 19
    I should say the schematic and what was actually hook up doesn't make sense right..
  • ratio
    ratio Member Posts: 2,924
    Do you have a meter to check voltages with? I can speculate, but without verification you run the risk of damaging something.
  • LeSer
    LeSer Member Posts: 19
    I will borrow one tomorrow. Where should I take voltage off. Thanks !
    HVACNUT Member Posts: 4,195
    Thermostat connections at the boiler to Y and G, to R and W at the thermostat.
    Common (C) at the boiler connects to C on the thermostat. You NEED that C connection. I see a green wire there behind the thermostat sub base, so use that and you should be good.
  • LeSer
    LeSer Member Posts: 19
    I already tried the C to C and it doesn't work on existing wiring.

    But I will do Y-R and W-G, instead of W-W (currently) and C to C.

    I really dont know why W goes to W even though the schematics shows it shouldn't be hook up that way.

    Now im curious why its working on dumb thermostat, unless the existing wiring is somehow wrong
  • BoilOver2
    BoilOver2 Member Posts: 38

    Can you posted a picture of your ecobee wiring plate with what you've tried?

    Probably not the issue, but you have to hook up something to rc on the ecobee (at least the 3 model), even though on a two wire setup rh seems like the logical choice.

    That bit me over the weekend.
  • Jamie Hall
    Jamie Hall Member Posts: 17,061
    It works on a dumb thermostat because the dumb thermostat is simply a switch, nothing more. What you are looking for is the wiring combination which will properly power the Ecobee, which requires constant 24 VAC power, and which -- with a third wire -- will behave like a simple switch.

    I have to admit that I find the wiring diagrams which Ecobee supplies are... strange. And, honestly, I'd have to have one in hand to figure out which terminal on the Ecobee did what.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • LeSer
    LeSer Member Posts: 19
    I dont have any now.. I have a separate 24v adapter coming just in case I dont get it from the boiler. If i dont use it here, nest doorbell can use it.. just fyi ecobee 4 in my house R/R W/W C/C no issue.. I have the weils cga and labels are pretty clear. Thie weils peg/eg50 has slightly different setup.. Might not get testing done tonight, Xmas party at work... probably get home late.

    I had tested the cable in RC at one point, I went through the manual, they had mention that.. move from rh into rc
  • LeSer
    LeSer Member Posts: 19
    Got it working. Original wiring R to Y, W to W
    I added the 24v to rh and rc.

    I tried the RY and WG like schematic - did not work. Wonder if they fk up wiring behind label