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  1. #1

    Does anyone know what W stand for with heat on the circuit board?

    Like w is for heat and Y is for cooling
    What is the reason W is used to indicate heat?

  2. #2
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    Nov 2004
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    Practically Canadian ehh.
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    675
    This may sound naive but I always assumed the letters stood for the colors used: Red Green Yellow White

  3. #3
    Join Date
    Dec 2003
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    SLC
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    I don't know what it stands for, but I do know that Honeywell created the R,W,Y,G,C terminal designation years ago.

  4. #4
    Join Date
    Mar 2007
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    NW AR
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    2,475
    I thought it was wire color too.

  5. #5
    Join Date
    Feb 2005
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    Where it's dark & damp
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    I don't know what it stands for but I remeber working on some old York package equipment that had different terminal designations. I thought the old designations made more sense than the current ones. I believe it had a F for the fan but don't remember the others. If it weren't for one of the units still having a wiring diagram I wouldn't have known what the terminals stould for.

  6. #6
    Join Date
    Nov 2005
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    573
    Yes there are some older equipment that does not use the standard wiring colors we are use to.

  7. #7
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    Sep 2005
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    Atlanta GA area
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    I am not sure if this was smoke or not, but this is what I was told at a Trane tech school:

    The instructor is in his 60's, an old marine. He said that back when central ducted forced air was ONLY heat, there was a two wire line to the millivolt (remember those) thermostat. The colors of the wire were red and white. So since red is always power, then white became heat by default.

    I have seen a lot of folks that use the blue for cool (put blue on the Y terminal).

    I really do not care which code folks use, as long as they use the SAME code all the time. Makes it a lot easier to trouble-shoot things.
    GA-HVAC-Tech

    Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8

    2 Chronicles 7:14

    Quality work at a fair price with excellent customer service.

  8. #8
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    Jan 2004
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    Earth
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    4,879
    Quote Originally Posted by ar_hvac_man View Post
    I thought it was wire color too.
    What color is C?
    A Diamond is just a piece of coal, that made good under pressure!

  9. #9
    Join Date
    Sep 2005
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    Atlanta GA area
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    Quote Originally Posted by frozensolid View Post
    What color is C?
    Trane or Rheem/Ruud?
    GA-HVAC-Tech

    Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8

    2 Chronicles 7:14

    Quality work at a fair price with excellent customer service.

  10. #10
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    Quote Originally Posted by ga-hvac-tech View Post
    I am not sure if this was smoke or not, but this is what I was told at a Trane tech school:

    The instructor is in his 60's, an old marine. He said that back when central ducted forced air was ONLY heat, there was a two wire line to the millivolt (remember those) thermostat. The colors of the wire were red and white. So since red is always power, then white became heat by default.

    I have seen a lot of folks that use the blue for cool (put blue on the Y terminal).

    I really do not care which code folks use, as long as they use the SAME code all the time. Makes it a lot easier to trouble-shoot things.
    I always loved it when there'd be one set of wire colors on the roof, and when you got to the stat down below, things changed. Somewhere midway a hidden splice, with colors switched mid-stream to make the tech's day all that much more fun.

    Also loved how Lennox would use different designations for their low voltage. Also made things fun. Personally I like when the colors are literally followed along with what each terminal stands for.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  11. #11
    Join Date
    Mar 2004
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    CHICAGO SUBURBS
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    464
    I know what you mean Shophound, I had a RTU call once at a medical office. Dead of chicago winter. Frozen evap coil. Get it thawed out and check low volt wiring. 4 wire R,W,G,B instead of Y but it's all good as I use this 4 wire type myself. RTU was wired correctly but at the thermostat someone put the blue wire on the blue terminal. uh oh. I fixed it and told the nurse what was wrong only to get chastised by her because her hubby installed that and he is a Union electrician and can surely install a simple stat. What can I say but when I arrived it didn't work and now it does.
    Some people swear by me and some at me

  12. #12
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,259
    Yeah Tim, it never ceases to amaze me that electricians know more about the INTERNAL wiring of an HVAC system than a licensed HVAC guy does...

    Kinda like liberals and politics and life... But I digress...
    GA-HVAC-Tech

    Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8

    2 Chronicles 7:14

    Quality work at a fair price with excellent customer service.

  13. #13
    Join Date
    May 2006
    Location
    Kennett, Missouri
    Posts
    997
    yeah like the elctrician that wired a couple air handlers. Split the two blacks to each leg coming in and ran the two yellow right to ground. hmmmmmmmm

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