CT 3400 with a weather bug select 90 plus


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Old 01-08-13, 04:28 PM
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CT 3400 with a weather bug select 90 plus

Hello,

I'm in a house that has a weather bug select 90 plus gas furnace. I do not know how old the furnace is. I am trying to hook up an old Honeywell CT3400 programable thermostat to the furnace. When I hook it up, no matter what settings apply to the thermostat, the heat will turn on but it will never stop. I can put the switch on the thermostat from heat to off and the thermostat will turn off. But when I put it to "heat" it just never turns off even though the temperature is much higher than the setting of the thermostat.

The non programable thermostat that I have had installed before works just fine. It is a non programable Honeywell basic thermostat. Inside the cover it says "Honeywell class 2 30V MAX" ON the front of the back panel it has some number "0247 CT41A444"

I am wondering what the problem is and do I have to install a relay? I do not know if there already a relay in the house already. I just don't understand why this programable thermostat won't just work. By the way, I know that it is not the thermostat broken because I have two of the same model of the thermostat and it does the exact same thing for both. When I hook it up, the heat turns on but it doesn't turn off.
 
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Old 01-08-13, 04:50 PM
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How was the old thermostat wired? How do you have the new thermostat wired? Are the settings correct on the back of the new thermostat?
 
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Old 01-09-13, 03:17 PM
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I hooked up the wires exactly the same as it was in the other thermostat. Green to G, Yellow to Y, Red to R, and White to W.

I also tried every configuration on the back of thermostat and it did the same thing no matter what.

Hooked up the old thermostat and it works fine.
 
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Old 01-09-13, 04:03 PM
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Bad thermostats........ That is the only answer. All the thermostat does is connect
R to :
G = fan
W = heat
Y = cool
 
 

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