Carrier HH18HA495 Limit Switch

The Carrier HH18HA495 Limit Switch is a critical safety component designed for precise thermal monitoring in high-efficiency gas furnaces. As a genuine OEM flame rollout switch, it is factory-calibrated to an opening temperature of 350°F. When a rollout condition occurs—where flames deviate from the heat exchanger and reach the burner vestibule—this switch interrupts the power to the gas valve, preventing equipment damage and hazardous operating conditions. The HH18HA495 features a manual reset design, a vital safety requirement that forces a manual inspection of the heat exchanger and venting system before the furnace can be returned to service. This ensures that the root cause of the overheat condition is addressed by a technician rather than allowing the system to cycle automatically. Built to withstand the harsh environment of a burner assembly, this limit switch provides an exact fit for Carrier, Bryant, and Payne equipment, maintaining the original integrity of the furnace safety circuit.

• Precise Thermal Response: The 350-degree trip point provides a reliable safety barrier against excessive heat in the burner compartment.
• Manual Override Protection: Prevents automatic restarts, ensuring a professional technician evaluates the system following a rollout event.
• OEM Engineering: This Carrier replacement part guarantees compatibility with existing wiring harnesses and mounting brackets without modification.
• System Longevity: Helps protect secondary heat exchangers and internal components from heat-induced fatigue and melting.

What causes this switch to trip?
A trip typically indicates a flame rollout condition, often caused by a restricted flue, a cracked heat exchanger, or excessive gas pressure. It requires a thorough combustion analysis.

Can I replace this with an auto-reset switch?
No. For safety and code compliance, a flame rollout switch must be a manual reset type to ensure the underlying technical fault is identified by a professional.

Is this compatible with other brands?
While designed for Carrier HVAC systems, it is also the standard OEM replacement for many Bryant and Payne furnace models. Always verify the part number in the service manual.

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.