I have a Honeywell RTH2510 series thermostat that I want to install in a condo with baseboard heating. I took off the very old thermostat that was previously installed and there are only two very thick red wires attached (Not sure of the specifics of the wires). I believe I can install one red wire in the R slot and the other in the W slot without worrying about which goes where. Is this correct? Then my next question is about the wires themselves. The wires are too large to fit into the terminals. I was wondering is there was a way I could attach a thinner more pliable wire to each one so I could then install the thermostat?
It's possible that the existing thermostat works on line voltage (120/240 volts), so you should be careful. Look up the model number on the internet, to determine what voltage the existing unit is designed for.
If the existing unit is line voltage, you'll have to replace it with a model that works at that voltage. The RTH2510 is designed for 24 VAC, not line voltage (120/240V). In fact, the description for the thermostat at Home Depot specifically says "Does not work with electric baseboard heat (120-240-Volt ) or multi-stage heating/cooling systems".