I live in a Condo which has heating controlled by a boiler system which sends hot water through baseboards along the wall. I am trying to install a new thermostat because I think the previous owners installed an old, junky one right before they moved out and did it incorrectly. We now have extremely hot temperature in our Condo all the time.

The current thermostat has two red wires going to it. But there are actually two black wires behind the thermostat that are just twisted together. I'm wondering if these black wires should be hooked up to the thermostat because they control a fan or something else important. There is a black and red wire which comes out of the right side of the box behind the thermostat and then another black and red wire which comes out of the left side.


Additional Info:

Location: Canada
Building: 2 years old
No A/C, just heat


~ Mark

Having trouble with the description. The new thermostat should be easy, because it is just a switch that breaks the low voltage connection to the boiler. The additional wires in the box are confusing to me as well, so what I recommend is to turn the boiler off with the emergency switch or breaker. Allow all the baseboard heat to cool (this may take an hour or more). Next disconnect the two wires from the thermostat (don't worry about the ones behind just yet). Isolate the two wires with wire nuts to make it safe, then turn the boiler back on. Feel the pipes on the baseboard to determine if they are getting hot. If not the two wires are enough. Turn the boiler back off and hook up the new thermostat using the "R" and "W" terminals. If the baseboard gets hot with those wires disconnected, the old, Junky thermostat is indeed hooked up incorrectly, and you will need to write in with more information about the other wires.

I hope this helps https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html#post268211