I'm trying to install a Honeywell 9585WF. I have a common wire which is connected and was in use on my old thermostat. The source is from the boiler which is seperate from the A.C.. Doesn't work. I'm now told C needs to come from the A.C.. Is that true. null

Question

Honeywell Support · Accepted Answer

Hello Tony. It appears you have a two transformer system. The Honeywell - Smart Color Thermostat with Wi-Fi Connectivity - Silver must have the common (C) from the A.C. transformer. The C wire can not come from the boiler transformer when you have A.C. Hope this answers your question.

Answered by Honeywell Support 7 years ago

“I'm trying to install a Honeywell 9585WF. I have a common wire which is connected and was in use on my old thermostat. The source is from the boiler which is seperate from the A.C.. Doesn't work. I'm now told C needs to come from the A.C.. Is that true.”

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