2 wire thermostat with heat and ac

Old 01-14-14, 07:54 AM
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2 wire thermostat with heat and ac

Hey all,
I just moved into a condo and I am trying to change my Honeywell T651A to a digital thermostat. This old thermostat only has two wires connected on the back of it. The thermostat only controls when the units, in each room, turn on and off and it has a switch on the bottom for heat/cool. The condo building controls when the heat is turned on in the colder months and cooling in the hotter months.

Regarding the actual units in each room, there are switches for fan operation on each individual unit itself (Low, medium, high and off) (I have a heating/cooling vent in each room). I've attached pics of the back of the thermostat to better clarify my problem. I've done some research and cannot seem to figure out what kind of unit I need or if it is at all possible? Any help would be greatly appreciated!
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Old 01-15-14, 12:46 AM
Join Date: Mar 2006
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You have a Honeywell series 60 thermostat. Series 60 denotes a line-voltage model and the particular model you have is single pole, double throw switching with a heat/cool selector switch. You will not find a compatible thermostat in any big box mega-mart homecenter. There MAY be a compatible digital model but it would only be available through an authorized HVAC service company.

Or, with a bit of fiddling you could build an adaptation circuit to allow the use of a standard low-voltage heat/cool thermostat with that arrangement. It might look rather ugly on the wall, though.

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