Most two-wire thermostats wire have a red and white wire encased in a brown insulated coating. Strip the red and white wires back about 1/4 inch at both the thermostat and the furnace ends. Connect the white wire to the W terminal on the furnace and thermostat.

What wires go where on a thermostat?

The white wire underneath your thermostat connects to your heating system. It terminates at your air handler or furnace. The white wire connects to terminal W in industry-standard thermostats.

What are S1 and S2 wires on thermostat?

S, S1, S2: These wires run directly outside and provide outdoor temperature information to the thermostat.

Can you replace a 4 wire thermostat with a 2 wire thermostat?

Yes, you can connect a four wire thermostat to this setup. Connect the white wires in the same manner as the black wires are connected.

Can you wire a double pole thermostat as a single pole?

You can use double-pole thermostats as single pole units. Most double-pole line voltage thermostats will break only one pole when cycling on and off. Connecting the poles together in parallel as you planned will not work.