Thermostats

A thermostat regulates the operating temperature of a boiler, water heater or burner by opening and closing a circuit at a set point. Depending on the appliance, it may govern primary heat output, act as a high-limit safety cut-out, or control domestic hot-water temperature. Units are typically mounted on the heat exchanger, flue collector or water outlet and are wired into the appliance control board.

Selecting the correct replacement requires the original order number where possible, but if that is unavailable the key parameters are the switching temperature or range, the temperature differential, the capillary length and bulb dimensions, the electrical rating in volts and amps, and the connection type. A cross-reference by manufacturer part number — including parts originally made for ACV, De Dietrich, Honeywell, Master or Resideo appliances — can be used to locate the matching part in this section.