Installing Ecobee4 but lack a C wire

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  #41  
Old 01-14-18, 03:44 PM
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Hi Pete & Doug,

Finally got the Stat working on the weekend. Thanks for all of your help!

For anyone potentially following this thread, below is the connection for my Ecobee4 based on the photo in this link - https://drive.google.com/open?id=12t...2VsYOBn1SWkwYJ

A to W1
B to Rh
C to C
D to Rc

With the connections as above, my Ecobee4 functions as normal.
 
  #42  
Old 01-14-18, 04:45 PM
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That means 24vac was not present on on the A and B terminals with the stat connected.
 
  #43  
Old 01-14-18, 04:58 PM
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Hi Pete,

A to B showed 27V
 
  #44  
Old 01-15-18, 10:34 AM
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Dane you are a true gentleman for posting back here ! (Well at least a pretty good gentleman anyway– lol)

guys take a look at posts #21 and #22. It looks to me like things may have gone off the track at that point. It seems to me the results of the tests in post #21 indicate that A=R and B=W. But post #22 indicates A=W and B=R.

If that’s the case and truly A=R and B=W, then from post #41-

A to W1
B to Rh
C to C
D to Rc

means it is connected now as:

R---->W1
W---->Rh
C---->C
+24vac from transformer---->Rc

That would explain why the ecobee now turns on because Rc has +24vac and the common(C) is connected - but does it actually control the heat now. Seems like that would be a problem – to me anyway.

But Dane – if you have already tested this with the heat and it works then just trash this entire post –lol.
 
  #45  
Old 01-15-18, 08:40 PM
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Hi zoesdad, I followed the Rh and W1 suggestions based off Pete's explanation. He obviously has much more of an idea than I do, so I never questioned it. Hence I never tried swapping the 2 thermostat wires to see if that would turn anything on.

Thermostat appears to be working normally, but we're in the middle of Summer (temps over 100degF), so haven't really had a chance to run for any decent length of time.
 
  #46  
Old 01-15-18, 09:32 PM
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Z..... is absolutely right.
I wrote the right thing but transposed the letters on the diagram.

You can change the wiring at the stat to reflect the correct wiring.
Your stat will run ok the way it's wired.

I went back and corrected that diagram and posted it here too.
I added (R) to the D terminal as that is the same as R.

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  #47  
Old 01-15-18, 11:22 PM
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So it's currently wired incorrectly? How come it still works?

Should I re-wire as per the most recent update?
 
  #48  
Old 01-16-18, 01:01 AM
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It works because the R and W (A&B) are closing the circuit and Rc and C (C&D) are supplying 24v.
 
 

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