Ruud 47-104990-05 Gas Furnace Limit Switch Auto Reset Spst

Product Description

The RUUD 47-104990-05 is a single-pole, normally closed limit switch designed for use in gas furnace applications. It opens at 160 degrees F and automatically resets at 140 degrees F, providing reliable high-temperature protection for the heat exchanger and burner assembly. Rated at 120/230 VAC and 15/10 amps, this SPST auto-reset switch mounts via a 3-inch insert and is identified by its red color coding. Licensed HVAC technicians install this component as part of routine furnace safety-system maintenance or replacement of failed limit controls.

This limit switch is intended for residential gas furnace installations where automatic thermal limit protection is required. It is specified for use on the R801PA100417MSA and R801PA100417MXA gas furnace models. The auto-reset design allows the switch to return to the normally closed position once the furnace plenum or heat exchanger temperature drops below the reset threshold, minimizing nuisance service calls caused by manual-reset requirements.

Key Features

• Opens at 160 degrees F, resets at 140 degrees F for precise thermal limit control
• SPST, normally closed, auto-reset configuration
• Rated 120/230 VAC at 15/10 amps for compatibility with standard gas furnace control circuits
• 3-inch insert mount for direct OEM-style installation
• Red color coding for quick field identification
• Single-pole design simplifies wiring in low-voltage furnace control boards

Compatibility

Specified for use on the RUUD R801PA100417MSA and R801PA100417MXA gas furnace models as an OEM-replacement limit switch.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with the appliance manufacturer instructions and applicable local codes. Disconnect all power to the furnace and shut off the gas supply before removing or installing any limit switch. Verify the replacement switch orientation and insert depth match the original component before securing. Do not bypass or jumper the limit switch under any circumstances during testing or commissioning.

Technical Specifications

• Switch Type: SPST, Normally Closed, Auto Reset, 1-Pole
• Open Temperature: 160 degrees F
• Close (Reset) Temperature: 140 degrees F
• Voltage Rating: 120/230 VAC
• Amperage Rating: 15/10 amps
• Insert Size: 3 inches
• Color: Red
• Length: 5.6 inches
• Width: 3.05 inches
• Height: 2.15 inches
• Weight: 0.08 pounds

Standard Information

• Brand: RUUD
• Manufacturer Part Number: 47-104990-05