Hi, I'm replacing an old baseboard heater and thermostat. I've followed the thermostat instructions and wired it to the heater using the two black wires leaving the two red wires to connect to the wall. There are four wires, two black and two white plus the ground wire coming out of the wall. Should I connect one set (black/white) to the thermostat and cap off the other?

Are you using a single pole wall thermostat? If so is the power ran to your heater or thermostat?

No, The thermostat installs into the baseboard itself. There was a similar yet antiquated unit that my wife removed so I didn't see the setup. The power runs into the thermostat, through it into the heater

Double pole thermostat or single? If it's a single pole connect the black wires to the thermostat and cap the red or white wires. If it's 2 pole you want to connect the power to the line side of thermostat and the heater wires to the load side of the thermostat.

Sorry I messed up on the single pole answer... connect the black wire to one lead on the thermostat and the red wire to the heater... now connect the other wire from the thermostat to the second lead from the heater... let me know if you need more help.

You may see Line and load marked on the thermostat. If you do, line goes to the fuse and load goes to the heater.

Since this is likely a 240 ckt, you need to interrupt both legs.

Power needs to flow thrugh the switch. If the wires to the heater are black and white, then the whites on the switch should interrupt the white and the blacks interrupt the black.

What happens, is the thermostat disconnects both poles in the off position. In the on position, one pole is controlling the power to the heater and the other pole is on all the time.

Thanks Keith!