Resideo L4006B1007 Aquastat Controller 320819-301 Key Benefits Precise 5kW Output:

Key Benefits Precise 5kW Output: Provides consistent supplemental heating to assist heat pumps during defrost cycles or extreme outdoor temperatures

As an in-shot furnace burner

or if the furnace pilot won't stay lit even after cleaning

and Pennco brands

Resideo L4006B1007 Aquastat Controller 320819-301 Key Benefits Precise 5kW Output:The Resideo L4006B1007 Aquastat Controller is a professional grade immersion temperature controller designed specifically for circulator application in hydronic heating systems. This immersion device features a 3 8" x 2 7 8" copper bulb sensing element that provides precise thermal response for regulating or limiting the temperature of liquids in boilers and storage tanks. Configured with SPST contacts that make on temperature rise, the L4006B1007