Replacing old ChemoTherm III with Lux, but confused on G vs. B/O wires


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Old 04-28-13, 10:34 AM
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Replacing old ChemoTherm III with Lux, but confused on G vs. B/O wires

I am replacing a Honeywell ChemoTherm III with a Lux TX9000TS programmable thermostat, but am not sure how to proceed since I lack a "G" wire. The heating/cooling unit is a Synder General single-stage heat pump from when this loft went condo in 1989. The instructions for the Lux thermostat call for a wire to go to the "G" terminal, another to either "B" or "O" terminals but not both, one be jumpered between Rc/Rh terminals, and fourth be jumpered between W/Y terminals. However, the Honeywell has only three wires going to it, each in pairs, to the R/Rc (jump), W/Y (jump), and B terminals. Should I just connect the current "B" terminal wires to the "G" terminal of the Lux??? Or jumper between those terminals?? If it helps, the heat pump's panel labels the wires a little differently than the Honeywell: it's "W" terminal wires go to the Honeywells' "B" terminal, while its "Y" terminal wires to go Y jumped with W, and its "R" terminal wires to R jumped with Rc. Thanks much!
 
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Old 04-28-13, 10:43 AM
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Making it simpler:

Instructions ask for:
G (fan/common) *** Confused on this
B or O (changeover) *** Confused on this
Y/W
Rc/Rh

Old Honeywell has only (two pairs of wires to each terminal):
B
Y/W
R/Rc

Synder Pump out terminals
W (goes to the Honeywell's B terminal)
Y (goes to the Honeywell's Y/W terminals)
R (goes to the Honeywell's R/Rc terminals)
 
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Old 04-28-13, 12:31 PM
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Old = New
Y,W = Y,W
B = B
Rc/R =RC,RH



You do not have the ability to run Fan Only without G.
You must use batteries with out a C wire.

If you have extra wires, or want to pull new wire, you can add these features.
 
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Old 04-30-13, 11:48 AM
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Keep the chronotherm III if it still works -> it's far superior to just about every consumer stat available now.
 
 

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