I am installing a wall heater in a room. The heater has a ground wire and a black and red wire. How do you hook it up to 240 volts? Do I need to run four wires, three wires? I have a double breaker at 20 amps already in the circuit breaker panel but what do I need to hook up power. Does one of the wires on the heater need two power wires to make the 240?