Original message
| joniss
 |  "Trane to Honeywell RTH7400"
, posted Tue 8 Apr 20:11  
I am looking over the forum and have not seen this posted yet so here I go.
I am in the process of changing my standard trane BAYSTAT239A thermostat over to a programmable Honeywell RTH7400. I looked over all the information and cannot find wiring diagram for an 8 wire setup. My original was wired as follows.
X2-Black
o-Orange
G-Green
Y-Yellow
T-Brown (No Mention of this on their diagram at all)
R-Red
W-White
B-Light Blue
I hooked up everything I could find except for the blue. Was able to get fan to come on and went to make changes to the 190 and other programming and now nothing comes on. If anyone has a diagram or can point me in the right direction I would greatly appreciate it.
Regards,
Jon C
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Replies:
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| joniss
| "Re(1):Trane to Honeywell RTH7400" , posted Wed 9 Apr 22:10
I did find what looks like a screw in fuse on the left side of the panel above the blower. It has what appears to be a white fuse GMQ 3 2/10 is the only thing I can read on it. Will see if I can find one at either Grangers or A/C place. I think maybe that is the only problem with the system since I miswired it. Well that is what I am hoping.
The unit is a Trane model number is TWE048C140B3
Thanks for all the help
Jon C
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| | Houston204
| "Re(2):Trane to Honeywell RTH7400" , posted Wed 9 Apr 22:16
You might try Radioshack.
"Tip of the Day" Remember to remove power first.
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| joniss
| "Re(1):Trane to Honeywell RTH7400" , posted Wed 9 Apr 08:32
Well I couldn't wait to see so I put the old thermostat back in and turned the breaker back on and nothing. All wires are correct and the system does nothing at all.
Any ideas where to start? I don't know if there is a low voltage fuse somewhere and don't know exactly where to start looking. Any insight as to where to start please let me know. I sure hate having to call out the AC guy to replace something like a transformer. Any help would be appreciated.
Thanks
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| joniss
| "Re(1):Trane to Honeywell RTH7400" , posted Wed 9 Apr 08:02
It looks like I had the o/b and c wires reversed. When I first turned the system on and the thermostat was set to all defaults it seemed to work fine. Fan manual came on and off and the compressor came on when I turned down the temp. When I went into the system and made the changes to the 170 and 190 options is when it stopped working. So I unplugged the thermostat and went over the wires again and found the o/b and c problem and swapped them to the correct posts. Now the system does nothing at all. I think maybe the thermostat was dammaged by the incorrect wiring. When I get home today I will put back the old tran therm and make sure all is well with the system and then swap out the possible bad thermostat and see what I come up with. My only question was about the T wire and am wondering why it is not needed anymore? I had read another post and someone else had the same problem and he fixed it by unplugging the new thermostat installing the old one and then back to the new one. I think you replied to his posts also. Just dont want to get into some kind of continuous loop where I need to hook up the old thermostat jump up and down a few times and then hook up the new one.
Thanks for the reply.
Jon C
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| | Houston204
| "Re(2):Trane to Honeywell RTH7400" , posted Tue 8 Apr 23:05
Blue is common. If you didn't wire it in and it shorted to any other wire, it damaged your transformer.
It is possible that you only lost a fuse in the air handler, but Trane was slow to start using low voltage fuses.
"Tip of the Day" Remember to remove power first.
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| | joniss
| "Re(3):Trane to Honeywell RTH7400" , posted Thu 10 Apr 19:03
Well I was able to find the fuse for the trane unit at Graingers and sure enough that's all it was. I used the old stat to test and then installed the new RTH7400 and all is working like a charm. Sure is nice to have someon to point you in the right direction. Appreciate your help houston204.
Thanks
Jon C
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| | Houston204
| "Re(4):Trane to Honeywell RTH7400" , posted Fri 11 Apr 00:12
You are Welcome.
"Tip of the Day" Remember to remove power first.
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