Replacement Options for Honeywell T651A

Steven Mitchell
last month
last modified: last month

Hi there,

I am trying to figure out best options for replacing an old Honewell T651A 2028 thermostat in my condo built in 1970. The thermostat has 3 large wires (I assume 120V) that are screwed into three terminals on the back of the thermostat labeled C (Common), Heat, Cool.

My unit uses hydronic heating and cooling and the HOA/Maintenance Crew controls which is on via a central water heating and cooling system. I simply set the temperature I want and the system decides whether it should blow air over the water pipes above my kitchen. In the winter, when heat (hot water in pipes) is on, if the room temp is 60 and I set the thermostat to 65, then it blows air and heated air comes out. In the summer, when A/C (cold water in pipes) is on, if the room temp is 75 and I set to 70, then it blows air and cooled air comes out.

I would like to know if there are any options out there for a thermostat that doesn't look like it belongs in a 1970s electronics museum. Even a simple white thermostat with a temperature control knob would be great. I assume I need a replacement that is Line Voltage, Mechanical, and Single Pole (doesn't need an off option). I've looked around online and even called Honeywell and the only answer I get is that I have to buy an identical thermostat in this case.

Otherwise, are there any good options for having an electrician convert the wiring to modern thermostat wiring so that I can use something that at least looks normal and has a digital display?

Many thanks for any advice or guidance!

-Steven in Denver

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