Actually is is better to use 220V if the heater allows for it. Having a higher voltage actually lowers your current draw (amps) if the wattage and resistance are the same in both heaters. Also, using 220V instead of 110V actually can help to keep your panel current draw (amps) even on each line.

It depends a little on the Thermostat it self. Some 220V thermostats only break one pole, others will break 2 poles. If there is only 2 wires (or terminals) it is a single pole thermostat. For this style, you will only interrupt one of the 2 hot wires and the other line goes directly to … Read more