Resideo L4008E1040 Controller

The Resideo L4008E1040 is a heavy-duty High Limit Aquastat Controller engineered for precise temperature regulation in hydronic heating systems, storage tanks, and industrial boiler applications. This immersion-type controller features a Single Pole Single Throw (SPST) micro-switch designed to break the circuit on temperature rise, providing critical over-temperature protection. With an operating range of 130-270°F and a factory-set stop at 250°F, it ensures equipment operates within safe thermal parameters. The unit utilizes a 66-inch liquid-filled copper capillary and a 3/8" x 2-7/8" remote bulb sensing element, allowing for rapid response to temperature fluctuations and flexible installation in either horizontal or vertical orientations. This manual reset aquastat is a staple for technicians requiring a reliable safety limit that refuses to automatically cycle after a high-limit trip, forcing a manual inspection of the system. Its rugged construction and UL/CSA listed status make it a standard field-replacement for many legacy Honeywell and Resideo high-limit controls.

• Precise Safety Control: Features a manual reset mechanism that ensures critical high-limit conditions are addressed by a technician before system restart.
• Superior Sensitivity: The 66-inch capillary and copper remote bulb provide rapid thermal response for liquid immersion or duct air sensing.
• Versatile Mounting: Designed for both horizontal and vertical mounting to accommodate tight equipment footprints and varied tank geometries.
• Technician-Friendly Calibration: Includes a visible control point scale and an external adjustment screw for simplified field settings.
• Universal Compatibility: Suitable for 120V and 240V applications, handling up to 8.0A full load at 120Vac.

What is the difference between an L4008A and this L4008E model?
The L4008A usually features an automatic reset, whereas the L4008E1040 is a dedicated manual reset high limit. The manual reset is a safety requirement in many jurisdictions for boiler high-limit protection to prevent dangerous cycling.

Can this be used to sense air temperature?
Yes, while primarily used for liquid immersion in boilers and tanks, the remote bulb design allows the Resideo L4008E1040 to sense duct or outside air temperature in specialized HVACR applications.

Does it come with a heat-conductive compound?
Standard high-limit aquastat installations typically require heat-conductive grease when using a well. Most Tradeline units include a tube of compound to ensure proper thermal transfer between the sensing bulb and the immersion well.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.