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I installed a new Honeywell C87N today. All went well, no probelms with the installation. The reason I changed the one I have was the heat just never stops running. This never happened before and just the other day it starting working in this manner. I doesn't shut off even if I put it on off the thermostat still keeps running. We live in a Condo and the furnace is in a separate building. The change didn't make any difference accept that it is new. Please help. The only way I an get ir to shut off is to trip the breakers.

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Hello brandaleepup,
Your problem may be at the furnace control end and not your thermostat. To determine that, simply unhook the two wires from your thermostat so that they do not make contact. When they are electrically opened like that, your furnace should shut down. If it doesn't, then the problem is at the furnace control board. You may have a relay that is staying on even when power to it is disabled.
Hope that helps...

Posted on Nov 28, 2008

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