Heat Pumps and Electric Heating - Honeywell Wiring - RTH7500 (new) and CT3000 (old)
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Hauger
04-02-08, 10:55 AM
Here's a nifty little question for everyone. I just bought a new house, complete with a wonky and hardly working Honeywell Thermostat CT3000 (couldn't figure out the exact model) installed circa 1988.
I've since bought a Honeywell RTH7500.
When looking at the old install (complete with 1988 install guide), it looks as though the installer had taken the original thermostat, and jammed a couple wires together to make things work. Right now the connections are:
G - 2 wires twisted and connected, a Green and a Yellow
Y - 2 wires twisted and connected, a Red and a Black
W - One Wire. White.
B - Empty
R - One Wire. Black.
The old install places a Y or a C to the Y terminal. Given there's two there, I take it one is a Y and one is a C (guessing here).
The new Honeywell has a Y and a C.
Me, I'm confused.
I called Honeywell for some direction. We spent about 20 minutes trying to identify the existing thermostat, complete with us looking up the form number of the manual. I don't think they ever did figure out what model I had, but in the end their advice was to jam the two wires into the existing G into the new G. The same with the Y terminal (both in the Y now into the Y in the new one).
Does this sound right? I'm thinking I'm going to do it, but I really would hope it's right.
Thanks for any insight you can offer.
(P.S.: I took photo's of the existing thermostat, install guide, and install wiring....but they can't seem to be posted here).
I've since bought a Honeywell RTH7500.
When looking at the old install (complete with 1988 install guide), it looks as though the installer had taken the original thermostat, and jammed a couple wires together to make things work. Right now the connections are:
G - 2 wires twisted and connected, a Green and a Yellow
Y - 2 wires twisted and connected, a Red and a Black
W - One Wire. White.
B - Empty
R - One Wire. Black.
The old install places a Y or a C to the Y terminal. Given there's two there, I take it one is a Y and one is a C (guessing here).
The new Honeywell has a Y and a C.
Me, I'm confused.
I called Honeywell for some direction. We spent about 20 minutes trying to identify the existing thermostat, complete with us looking up the form number of the manual. I don't think they ever did figure out what model I had, but in the end their advice was to jam the two wires into the existing G into the new G. The same with the Y terminal (both in the Y now into the Y in the new one).
Does this sound right? I'm thinking I'm going to do it, but I really would hope it's right.
Thanks for any insight you can offer.
(P.S.: I took photo's of the existing thermostat, install guide, and install wiring....but they can't seem to be posted here).