RET room thermostats are typically used in conjunction with a boiler and wall hung radiator heating systems. However, they can also be used in other heating systems where reference room temperature is used to switch the heat source either directly or via zone valves.Room Thermostat, RET1001 - By turning the dial to the desired setpoint temperature, optimal thermal comfort in the room is achieved. The thermostat setting scale also includes a frost protect setting allowing for mini mal energy consumption while avoiding damage from freezing temperatures and a standby/off position. Room Thermostats, RET2001 - Temperature selection is digital from the setting ring that circles the large easy to read backlit display. Like the dial product RET2001 includes frost protection feature as well as holiday mode with setback temperature for energy saving while you are away