Upgrading thermostat: wiring disaster

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Old 10-06-16, 10:15 AM
J
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Upgrading thermostat: wiring disaster

I want to install a new smart thermostat and do not have a c wire run to my thermostat. I have a fairly new system but it was wired terribly. Currently my thermostat has W/E, RH(with bridge to RC), Y and G connected. The furnace has G, C, W, Y, R terminal. There are already wires to all terminals and C, W, Y all have 2 wires connected. Why are there so many wires. How can I deal with this mess and rewire? Can I disconnect all and simply run new wires?
 
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Old 10-06-16, 10:22 AM
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Welcome to the forums.

That's not a mess......that's the way it is. You are going to have two wires on C and Y because they go to the stat and the outside condensor. Now you will have three wires on the C terminal.

Do you have the extra wire needed to supply the stat with a C connection ?
 
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Old 10-06-16, 04:06 PM
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You are going to need to trace the wires that you have and document where each one goes. Two wires on W at the furnace can mean you have a heat pump or a humidifier or something odd.

Sometimes there is an extra wire that goes to the thermostat but is cut off or otherwise still in the wall.
 
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Old 10-06-16, 04:28 PM
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I hadn't addressed the W wire yet. I don't believe there's a heat pump involved as there is no O/B connection or wire for it.

I have a feeling the two W wires are stat and humidifier.
 
 

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