Resideo L4008E1040 High Limit Aquastat M/R W/Remote bulb 130°F-270°F | PartsHnC
The Resideo L4008E1040 is a safety device that prevents HVAC systems from overheating. It's a high limit aquastat with a remote bulb that detects the temperature of a liquid, usually in a boiler or tank. When the temperature reaches a certain level (130°F to 270°F), the aquastat's single pole single throw (SPST) switch opens, cutting off the power supply to the heating element and preventing potential harm.