Question about Honeywell Electronic Programmable Heat/Cool Thermostat - CT3300A100 Heater
I have removed my existing old thermostat. Into the old thermostat there are 2 white wires and 1 black wire (from the old therm.) connected. Then there are 2 black wires and 1 red wire (from the old therm.) connected. Then the remaining 1 black and 1 red wire (from old therm. are connected to a single black and single white wire from box.
How do I reconfigure that to attach to the 2 black wires on the new therm.?
You will have to have schematics from the old wiring diagram. Then you will have to confirm its consistency with actual old wiring before you can be sure that the wires run to the proper places on the old heater and a/c system. This sounds like a gas furnace and is simpler than a heatpump. Once you know what distinguishes the wires with the same color, you should label them and then you may call them a different color if they were wired with wrong wire colors. You may be in luck if you go to the furnace control box an look at the terminals.. They are usually labeled with a R for Red and W for white and Bl for Blue and B or Black. If you have other colors on these then it sounds that it was wired with wire spare wire by someone who knew what they were doing but neglected to leave a path for someone else follow.
You may be able to use a continuity tester of circuit tester to id these wires that are in question...
ie, once indintified, you can match with the requirements of the new stat.
Posted on Jan 13, 2009
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Posted on Jan 02, 2017
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