The Rheem PROTECH 47-104990-04K Automatic Reset Limit Switch is an OEM replacement temperature safety control designed for compatible Rheem and Ruud heating equipment.

Also identified by item number 47-104990-04, this board-mount limit switch is a temperature-actuated electrical component used to help protect heating equipment from excessive operating temperatures.

When the monitored temperature reaches the switch's specified opening threshold, the electrical contacts open to interrupt the applicable safety circuit. Once the temperature decreases to the designated reset point, the switch automatically returns to its normal operating state.

Featuring a board-mount configuration, the Rheem 47-104990-04K is designed for installation in approved equipment assemblies requiring this specific mounting arrangement.

This OEM replacement component helps maintain the manufacturer's intended temperature safety protection and electrical control operation when installed in compatible heating systems.

Key Features & Function

• Brand: Rheem / PROTECH
• Manufacturer Part Number: 47-104990-04K
• Item Number: 47-104990-04
• OEM Description: Limit Switch – Auto Reset (Board Mount)
• Genuine OEM replacement temperature safety component
• Automatic-reset operation
• Board-mount configuration
• Temperature-actuated electrical switching
• Supports furnace overtemperature protection
• Designed for compatible Rheem and Ruud heating equipment
• Equipment-specific electrical and mounting configuration
• Suitable for professional HVAC maintenance and repair

Product Details & Specifications

Specification Note: The exact opening temperature, closing temperature, electrical ratings, and board-mount dimensions have not been independently verified. Confirm these specifications using Rheem's technical documentation before installation.

HVAC Depot Pro Tip

An automatic-reset limit switch that repeatedly opens may indicate an overheating condition rather than a defective switch.

Before replacing the Rheem 47-104990-04K, inspect the heating equipment for abnormal operating temperatures, restricted airflow, or electrical problems.

Recommended diagnostic checks:

1. Confirm the complete equipment model and serial number.
2. Verify the original limit switch part number.
3. Inspect the air filter and airflow restrictions.
4. Check blower motor operation.
5. Inspect the heating assembly for overheating.
6. Examine electrical connections and wiring.
7. Inspect the mounting board or bracket for damage.
8. Test switch operation according to manufacturer procedures.
9. Verify the replacement has the correct temperature rating and mounting configuration.

HVAC Depot Pro Tip: Board-mounted temperature switches must match the original mounting design and thermal sensing position. A switch with the same general appearance may have different temperature ratings or electrical characteristics.

Important: Never bypass or jumper a furnace limit switch. Repeated safety trips require diagnosis and correction of the underlying overheating condition.

Disconnect electrical power before servicing. Installation and testing should be performed by a qualified HVAC technician.

Equipment / Model Compatibility

The Rheem PROTECH 47-104990-04K is intended for select Rheem and Ruud heating equipment requiring this specific OEM automatic-reset board-mount limit switch.

Exact compatible equipment models have not been independently verified.

Before ordering, confirm:

• Complete equipment model number
• Equipment serial number
• Original limit switch part number
• Required opening and closing temperatures
• Automatic-reset configuration
• Board-mount dimensions
• Electrical terminal arrangement
• Manufacturer-approved replacement information

Compatibility Notice: The 47-104990-04K is not a universal furnace limit switch. Confirm manufacturer-approved compatibility before purchasing.