I have a Mears M611WT single line thermostat with thermometer. The old thermostat had a black and white wire and a copper neutral coming from the electrical box in the wall which was connected to a single pole 120/240 20 amp thermostat. The new Mears thermostat has a black and red wire and a thinner white wire. To what do I hook these three wires to the wires in the electrical box.