Allied Air 57W38 Furnace Limit Control Switch 150-180F

Product Description

The ALLIED AIR 57W38 is a red, auto-reset furnace limit control switch designed to protect gas and oil furnace heat exchangers from overheating conditions. The switch monitors supply-air temperature and opens the burner circuit when temperatures reach the upper threshold, then automatically resets once temperatures fall back within the safe operating range. Featuring a 3-inch insertion depth, it mounts directly into the furnace plenum or heat exchanger cabinet. The red housing makes identification straightforward during service calls. Licensed HVAC technicians install this part as a direct OEM-style replacement during routine maintenance or troubleshooting of high-limit fault conditions.

This limit control switch is suited for residential gas and oil furnaces where automatic high-limit protection is required. The auto-reset design eliminates the need for manual intervention after a nuisance trip, making it a practical choice for single-stage and multi-stage forced-air furnace applications. The 150-180 degrees F operating range covers common high-limit setpoints found in standard residential furnace configurations. It installs in the air-stream path of the heat exchanger section, where accurate temperature sensing is critical to safe furnace operation.

Key Features

• Auto-reset operation restores burner circuit automatically once temperatures return to safe range
• 3-inch insertion depth for proper plenum or heat exchanger mounting
• 150-180 degrees F operating range matches common residential furnace high-limit setpoints
• Red housing for quick visual identification during service
• OEM-style replacement form factor for straightforward swap-out

Compatibility

Designed as an OEM-style replacement limit control switch for residential gas and oil furnaces requiring a 3-inch insertion depth auto-reset high-limit control in the 150-180 degrees F range.

Installation Notes

Installation should be performed by a licensed HVAC technician. Shut off power to the furnace at the disconnect or breaker and allow the heat exchanger to cool completely before removing the existing limit switch. Confirm the insertion depth, temperature rating, and mounting thread match the original component before installation. Work should comply with applicable local mechanical codes and the furnace manufacturer's service documentation.

Technical Specifications

• Type: Limit Control Switch
• Used On: Furnace
• Reset Type: Auto Reset
• Temperature Range: 150-180 degrees F
• Insertion Depth: 3 inches
• Color: Red
• Weight: 1.0 pounds

Standard Information

• Brand: ALLIED AIR
• Manufacturer Part Number: 57W38