Heat Pump thermostat wiring


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Old 01-20-07, 08:42 AM
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Heat Pump thermostat wiring

A guy is selling lots of Honeywell T8411R heat pump thermostats on ebay, so this question might help others like me who have bought one.

My old thermostat is a Columbus Electric analog wired like this:
X2: black
O: orange
G: green
Y: yello
T: tan
R: red
W (jumpered to U): white
B: blue
F: unused

I won't try this until I hear from you, but it looks like the Honeywell digital should be wired like this?
G: green
C: white
R: red
W1: unused but jumpered to Y
Y: yello
L: unused
W2: black
E: unused
B: blue
O: orange
This leaves my tan wire unconnected.

Does my educated guess work, or will it blow up my American Standard heat pump? Please let me know which wire is which so I don't do any damage. Thanks!
 
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Old 01-20-07, 10:07 AM
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I'm always hesitant to offer advice on digital stat hookups. Different systems or installs frequently have different ways of doing things. Sometimes you never know what you are getting into. In some cases a meter or actually tracing the wiring is necessary.

But I do see one problem, just from taking a quick look. On newer stats "o" and "b" are for the reversing valve. You cannot use both. In older systems and especially on Trane systems (who now owns American Standard), the "b" or blue wire is the 24v common connection from the transformer. You will have to track down this wire to the air handler to be sure. If so, then it would connect to the "c" terminal of the new stat.

I would also suspect the white wire should connect to "w2" and the black wire should connect to "e". This is assuming the black wire connects to a relay that energizes another set of heat strips. Again, you will likely need to track this down.

There are a few ways to do this.
Others will likely post with additional info.
 

Last edited by jim-connor; 01-20-07 at 10:32 AM.
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Old 01-22-07, 04:52 PM
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Thanks, Jim...a little followup since nobody else?

Out of 80 viewers, you were the only one with an answer?

Either means, everybody else thought you were right, or you're the only one brave enough to help. Either way, thanks!

Based on your advice, here's what I did:
1. Found 24v between red and blue, so obviously blue is common, "C" and red is transformer hot.
2. Hooked up as follows:
G=green
C=blue
r=red
W1 Jumpered to Y by manufacturer
Y=yello
L unused
W2 = white
E=black
B unused
O orange
Brown wire previously connected to "T" on old stat is unused
3. Cooling works great.
4. Heat works great -- measured 110 degrees at register
5. Emergency heat works, but measured 90 degrees at register.

Seems like maybe "heat" and "energency heat" are reversed?

Please advise. Thanks so much.
 
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Old 01-22-07, 09:48 PM
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Wink

Like said that B on Coleman ,GE,Heil, Trane, and York are common.

4. Heat works great -- measured 110 degrees at register
This is not right for sure. So yes you have the elements comeing on with the heat pump here.Could be you pushed the tstat up to high and they came on
We try to get people to just set the tstat and let it alone. Unless you have the new tstats that are out. They dont turn on the elements for a pick up. This one when you set it back and then it turns on for the higher temp. The elements come on to help bring up the heat. So you use up what you saved in $$$ with the set back
 
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Old 01-24-07, 05:57 AM
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Connecting a heat pump to a digital stat can sometimes be a pain even for those who are experienced. So I wouldn't expect to see too many responses. It's also another item to diagnose on future service. In my experience, digital stats have a short life compared to the old mercury units that would usually outlast the entire system.
 
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Old 01-25-07, 05:42 PM
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Thanks, Jim

I think you were right -- I just gave it some time, and now everything seems to work well.

Lingering question: what did that brown wire previously attached to "T" and now attached to nothing do?

At one point, I measured 1.5 v to common from that brown wire...

Any suggestions?
 
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Old 01-25-07, 06:09 PM
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On My Cross -Reference sheet I have . All it said was

"T " Terminal From Old tstat Not used -Tape off

No way would I buy a tstat off Ebay

Im with Jim digital stats they dont last to long
 
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Old 10-19-09, 05:37 PM
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Thank you soo much. I have spent the better part of 8 hours trying to find the right wiring for my new thermostat. The idiot who took the old one off *my man* didnt label anything..... luckily i had seen it before he did so i saw most of it but i coudnt remember what black was.

What is L for anyway?
 
 

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