Trouble with Honeywell CT87N Thermostat


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Old 11-09-07, 07:04 PM
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Angry Trouble with Honeywell CT87N Thermostat

I started a simple job today to replace our programmable thermostat to a simple round, basic non programmable thermostat that everyone in the family can use without asking me for help.

For some reason, I can't get this simple thermostat to work. All of the dip switches are in the correct position. and the wiring is correct.

I can get the fan to work in the manual poistion, but can't get heat to work in Auto position.

If I jump the white wire to the red wire therby bypassing the thermostat, the heat comes on. But wired top Green, second position Green, third position Blue wire in Yellow position. This is exactly the same as my previous Thermostst.

I suspected the thermostst of being defective, so went and got another one with the same results.

Can any one suggest what is going on, or maybe have had some similiar experience that you would be kind enough to share?

Thanks in advance for your help!

Bob
 
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Old 11-09-07, 07:07 PM
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Unhappy Sorry, meant second position White!

Sorry posted without previewing.
 
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Old 11-09-07, 08:07 PM
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You made notes what wire went where??

R
W
G
Y

Go down to the furnace, and make note of what color go where.
 
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Old 11-10-07, 05:39 AM
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I labeled the wires before disconnecting.

Yes I made notes of what wires went where.

Labeled each wire before disconnecting.

I suspect the problem may be with the transformer?

I did have some problems while using the old thermostat. The furnace would sometimes come on then shut off after about 10 - 15 seconds.

One time when that happened, I went down to the furnace, and while removing the cover, the system came on.

Thinking that a loose connection to the transformer was the problem, I loosened the wire nuts one by one twisted the wires and reapplied the nuts.

One of my neighbors works in Heat /Air. He came over and verified the thermostst wiring was correct and suggested replacing the thermostat again.

My first post was after replacing the thermostat for the second time.
 
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Old 11-10-07, 06:00 AM
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Does everything work fine the whole time when you jumper the R and W wire?

What brand/model is your furnace, and age?
 
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Old 11-10-07, 12:14 PM
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Everything works fine

Everythine works fine when I jumper white to red.

Rudd, model no. UGDA-125A-GR
Serial No. F2491 3992

I replaced the relay this morning, still doesn't work.

Help!
 
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Old 11-10-07, 04:26 PM
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What relay are you talking about?

Sounds like an older model, so nothing fancy on it... Maybe just a bad run of t-stat???

Try another t-stat..
 
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Old 11-10-07, 06:42 PM
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Already on third Tstat

I'm already on my third one!

I'll guess I'll try another brand from another store.

All home depot has in manual besides the basic CT87N is a digital model.
 
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Old 11-10-07, 07:06 PM
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What was wrong with the old t-stat?
 
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Old 11-11-07, 08:29 AM
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double check the information that came with your new t-stat most likely there is a b option switch on the back that designates the type of system it will work with, set it correctly and you should be good to go.
 
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Old 11-11-07, 06:06 PM
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Bob,

What happens if you crank it all the way up?? Got another guy posting on the board, and he said he has to crank it up before anything happens on his.
 
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Old 11-21-08, 09:58 AM
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Having the same problem with Honeywell CT87N thermostat

Fan will not come on unless set at about 80 (hot). Manual fan works fine. Isn't a heat anticipator to work with as the unit is digital. Worked fine when I had the old mercury type.

Help.. it's getting cold
 
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Old 11-21-08, 10:17 AM
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Originally Posted by Hillsboro1 View Post
Fan will not come on unless set at about 80 (hot). Manual fan works fine. Isn't a heat anticipator to work with as the unit is digital. Worked fine when I had the old mercury type.

Help.. it's getting cold

Hill,

Need more info.. What do you have for heating equipment? (Gas furnace or heat pump or.. ???)
 
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Old 04-21-09, 09:47 PM
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my problem is different, but a problem. I have installed ct87n and works fine on and off,,but the lower needle showing house temp is at 78-79, and the upper needle to set temp is at 86 and it still is cycling a/c on when i dont think it should until house temp requires it.. I am on my second t/stat with same result so far. I dont know wht to do
 
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Old 04-22-09, 07:29 PM
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Is the room temp matching with another thermostat/thermometer?

When it does run how long does it run?
 
 

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