Another C Wire Issue - New Thermostat


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Old 06-24-14, 12:08 AM
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Another C Wire Issue - New Thermostat

I have an Aspen FMW56 48-015 (http://www.aspenmfg.com/documents/pr...ation-0608.pdf) and I'm trying to install a new thermostat that requires a c wire.

I have an extra wire running from the thermostat to the air handler unit, but don't know where to connect it for the C wire.

The thermostat is a Honeywell RTH9580WF (Honeywell Wi-Fi Programmable Thermostats | Wi-Fi Smart Thermostat (RTH9580WF)).

I need assistance to determine where it should be connected since i don't have a labeled terminal block with a "C". The blue wire that is loose on the Wire_Splice.jpg is the one that I'd like to use for the connection.

I've looked through many posts on different websites and don't seem to see anything that I can match up to my system setup for the wiring.

Thanks in advance for any assistance in helping get this setup properly.
 
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Old 06-24-14, 01:37 AM
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Welcome to the forums.

The brown wire from the transformer to the relays and to the A/C is your Common. I have it marked in yellow.

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Old 06-24-14, 08:43 AM
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Thank you for the quick reply.

Would the best way to tap into the common be to cut the brown wire coming out of the transformer and then wire nut in an additional wire to the thermostat?

Or is there a better way to handle this connection? Thanks again.
 
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Old 06-24-14, 08:59 AM
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If you follow the wire further..... doesn't it go to where the thermostat wiring is ?
I see a brown wire there with a wire nut that looks like might be the common connection.
 
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Old 06-24-14, 09:20 AM
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The brown wire goes from the transformer into the blower time delay, splits to the pump relay and then splits off from that.

I'm not in front of the unit, but from the picture, I believe it drops down and is wire nutted with a white wire as you mention.

If that in fact is the same brown wire that is wire nutted, would I be okay to tie into it at the wire nut even though it's been split off at the blower time delay and pump relay? The blue "C" wire going to the thermostat is right there.
 
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Old 06-24-14, 09:41 AM
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According to the service manual a tap was left for common with your other thermostat wires so that brown with the wirenut appears to be the wire in question.
 
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Old 06-24-14, 09:50 AM
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Thank you so much. I'll tie in the blue wire going to the thermostat tonight with the brown and white in the wire nut and confirm everything is functioning properly.
 
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Old 06-25-14, 12:14 AM
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Just finished up with the wire change and install and everything seems to be working properly as you advised splicing into the brown wire.

Thank you so much for you help in getting this resolved, it is very much appreciated.
 
 

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