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    Thread: Help me connect my programmable thermostat?

    1. Member SidVicious's Avatar
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      66Bug, 05Cavvy
      07-10-2012 04:58 PM #1
      Moved recently and the new house had a very chincy thermostat. Picked up a programmable one and would like a little help hooking it up.

      The pic below with the wires is what's on the wall now. The second pic is the new thermostat. I thought experimenting with the wires that are not obvious was a bad idea since it's 107* out today.

      If someone could tell me which wire goes where- that would be cool. Thanks guys.



    2. Moderator Rockhead261's Avatar
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      07-10-2012 05:55 PM #2
      The stat you purchased will not work properly. The existing stat is for a heatpump with supplemental (or two stage, or emergency) heat, usually a strip heater or even a burner. See that little sticker on the lower/left corner of the back of the new stat?? The new one will only work for a single stage heatpump and has no provisions for the supplemental.

      This is what's on the wall:

      G - Fan
      C - Common from transformer (usually needed for a clock on the stat, maybe just a junction)
      R - 24VAC from transformer
      W1 - First stage heat *
      Y - Cooling *
      O - Changeover valve
      W2 - Second stage/supplemental/emergency heat

      * W1 and Y being jumpered indicates that the compressor runs for both heat and cooling with O being the determining factor - when O is energized the system runs in A/C.

      Though I do not recommend it, you can connect the new thermostat (in heatpump mode) as follows:

      OLD - NEW
      G - G
      R - Rc (leave the Rc-Rh jumper in place)
      O - Y/O
      W1 - W/B
      Y - Y1

      C and W2 from the old stat will unused, hence no supplemental heat. The A/C will work normally, but the heat will be crap.

      Bring it back and get a two-stage heatpump stat.
      Cary

      '13 Sierra Denali 2500 CC D/A
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    3. Member SidVicious's Avatar
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      07-10-2012 06:14 PM #3
      Does it matter that we really don't use heat much here? The back of the new unit has a switch that says "System type" and can be switched from STD to HP (standard & heat pump, right?)

      I found instructions for 2, 3, 4 & 5 wire system set ups, but this house has 6 wires...

      Thanks for the help- I appreciate it

    4. Member SidVicious's Avatar
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      66Bug, 05Cavvy
      07-10-2012 06:43 PM #4
      Also- Should I jumper Y1 to W/B? W1 on the old unit is jumpered to Y, and you instructed W1 to W/B...

    5. Moderator Rockhead261's Avatar
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      07-10-2012 11:12 PM #5
      Quote Originally Posted by SidVicious View Post
      Does it matter that we really don't use heat much here?
      This is entirely up to you.

      The back of the new unit has a switch that says "System type" and can be switched from STD to HP (standard & heat pump, right?)
      Right. It should be switched to HP.

      I found instructions for 2, 3, 4 & 5 wire system set ups, but this house has 6 wires...
      As I said, you have two-stage heat. The thermostat is not equipped to handle it.


      Quote Originally Posted by SidVicious View Post
      Also- Should I jumper Y1 to W/B? W1 on the old unit is jumpered to Y, and you instructed W1 to W/B...
      Nope. W1 (1st stage heat) and Y (cooling) both do nothing more than start the compressor. The changeover valve (O) is what tells the system to cool or heat.

      Do yourself a favor - go out and get a two-stage heatpump thermostat. I wouldn't use the one you have there, and I know what I'm doing.
      Cary

      '13 Sierra Denali 2500 CC D/A
      '11 Outback 3.6R
      '12 FLHTCUI
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