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Ermostat manual T641A

I have a Honeywell T641A and would like to to see wiring Diagham for when it is on heat and then cooling Heatpump system with Ax Elec heat

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Re: ermostat manual T641A

Ok sir can you tell me your main problem?

Posted on Oct 16, 2007

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Replacing WHITE-RODGERS manual thermostat with 3 wires ( red, white, blue and installing Honeywell electronic thermostat RTH110B, how do I connect it? The heating is not central, baseboard heating.

I have only seen one Honeywell thermostat that would work with a 3-wire heating system.

I would replace it with a White-Rodgers 1F80-0471. They are about $100, but they are a good thermostat, and they work well with the 3-wire zone valves.

Most other thermostats have the "Y" terminal that you need, but do not control the zone valve correctly.

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What was the old thermostat labels and the wire colors that went to them?
The typical heatpump wiring Terminals are:
R = Red = Hot side of Transformer
C-B-X = Common side of transformer Depending on brand of heatpump
Y = Yellow = Cooling Contactor
G = Green = Furnace Blower
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You need to be sure where each wire comes from when you connect them to the new thermostat.
The best way to do that is to go to the furnace and see where they are connected. R-Y-G are probably correct, you need to see where the Blue wire comes from and determine what the X terminal was on the old thermostat.

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when you programed it did you go through all the setup #1-0 ,#3-0 ,#5-5 ,#12-1

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Look to see if you have it wired correctly with the o terminal be used and then check to see if you have a jumper wire between the Y and W terminal on the Base of the tstat where you hooked all the wires up.

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