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Hit the wall wiring for thermostat

I am installing an ecobee3 and was stumped looking at the wiring. I live in a rental, so I don't know how this was done. The control board has no yellow and the current thermostat has no common. Should I use the Power Extender Kit (PEK) and attach the wires as is on the board or do I call a professional to figure this out--Thx

Comments

  • ChrisJ
    ChrisJ Member Posts: 12,815
    edited June 2017
    The yellow is for cooling, I assume you do not have air conditioning?

    The black wire appears to be your common.
    Blue is your fan (G), often a green wire.
    Brown is your (W), often a white wire.


    The letters are right on the control board of the furnace.


    Curious, if you're renting, should you be messing with the thermostat?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    Zman
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,687
    Can you post a pic of the wiring diagram-probably on the board cover or the back of the furnace/blower door. If it doesn't tell us, can you also tell us the make/model of the furnace
    steve
  • ratio
    ratio Member Posts: 3,173
    "Electricity don't know no color." My Old Guy taught me that years and years ago. The colors are just there to make your job easier.
    WRT your stat, the names of the terminals are what's important, line them up like to like on the furnace control board. C is the common (power return), R is the 24 volt hot (power), G is the fan call, W is the heat call, Y is (would be) the cool call. R & C provide the power to the thermostat, if you run on batteries you don't need the C. I don't recommend batteries. Much better to be powered from the furnace if possible.
  • timglenn
    timglenn Member Posts: 4
    ChrisJ said:

    The yellow is for cooling, I assume you do not have air conditioning?

    The black wire appears to be your common.
    Blue is your fan (G), often a green wire.
    Brown is your (W), often a white wire.


    The letters are right on the control board of the furnace.


    Curious, if you're renting, should you be messing with the thermostat?

    That's my confusion. I do have central air. But where's the yellow. Long term lease and I pay for electricity. I can always swap back.
  • ChrisJ
    ChrisJ Member Posts: 12,815
    timglenn said:

    ChrisJ said:

    The yellow is for cooling, I assume you do not have air conditioning?

    The black wire appears to be your common.
    Blue is your fan (G), often a green wire.
    Brown is your (W), often a white wire.


    The letters are right on the control board of the furnace.


    Curious, if you're renting, should you be messing with the thermostat?

    That's my confusion. I do have central air. But where's the yellow. Long term lease and I pay for electricity. I can always swap back.
    What wires are at the thermostat?
    White red black blue?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • timglenn
    timglenn Member Posts: 4

    Can you post a pic of the wiring diagram-probably on the board cover or the back of the furnace/blower door. If it doesn't tell us, can you also tell us the make/model of the furnace

    I've changed thermostats before, but this is a mess. Once I can figure out what's going on...
    I've posted addition pics
  • timglenn
    timglenn Member Posts: 4



  • hot_rod
    hot_rod Member Posts: 16,274
    how many wires are there at the thermostat?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JUGHNE
    JUGHNE Member Posts: 9,750
    Looks like a hack job of quick replacement for failed components.

    Your AC yellow and common is tied (wirenuts) in between the Tstat and furnace control board terms. The AC lowvolt wiring might follow the line set which would help you ID the wires.
    The Y wire does not have to connect to the furnace board, only from Tstat to AC unit.

    If the Tstat wiring is simple to replace I would run 18-5 cable to the furnace.....and 18-2 cable for the AC spliced in an easy spot.
    This makes the color ID simpler.