Furnace Common Wire Question


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Old 02-08-14, 06:06 PM
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Furnace Common Wire Question

I've purchased a Honeywell Wifi thermostat that requires use of a "C" wire. The issue is that I currently do not have "C" wire but I do have one available wire that's currently not in use (wrapped around the base of the wire on both ends). My question is...I currently have a wire connected to the "C" terminal on the furnace end. Can I add this available wire to the "C" terminal even though there is one currently there. I've attached a picture for further reference.

Wiring


Thanks.
 
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Old 02-08-14, 06:29 PM
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yes you can if you put a meter to the R to C on that control module board should read a constant 24V...same as on the subbase at R to C
 
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Old 02-08-14, 06:45 PM
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Ok, so just to make sure I understand what you're saying... even though there is a wire connected to the C terminal, I can add an additional "C" wire going to my thermostat because it will still remain 24v?
 
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Old 02-08-14, 07:04 PM
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Yes, connect the unused stat wire to the furnace C terminal along with the red wire currently there.
 
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Old 02-09-14, 05:32 AM
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Thanks. What could that existing red wire going to C be?
 
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Old 02-09-14, 09:04 AM
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That wire goes to the outdoor compressor unit.

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Old 02-16-14, 07:52 AM
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It worked well... thanks!
 
 

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