Lochinvar L100208544 Hi-limit Outlet Sensor

Product Description

The LOCHINVAR L100208544 is a hi-limit outlet sensor designed to monitor water temperature at the heat exchanger outlet in hydronic heating and water heating equipment. This sensor acts as a high-temperature safety device, signaling the system control board to shut down the burner if outlet water temperature exceeds a safe threshold. It is a direct OEM replacement component installed by licensed plumbers, hydronic heating technicians, and mechanical contractors during routine service or system troubleshooting. Also referenced under part number TST20009.

This hi-limit outlet sensor is suited for residential and light commercial hydronic boilers and water heaters where outlet temperature protection is required. It mounts at the heat exchanger outlet port and feeds temperature data to the system control circuitry. Technicians typically replace this sensor when fault codes indicate a hi-limit trip or when diagnostic testing confirms an out-of-range resistance reading from the sensor circuit.

Key Features

• Monitors outlet water temperature to protect heat exchanger and system components from overheating
• Triggers burner shutdown when outlet temperature exceeds safe operating limits
• OEM replacement part cross-referenced as TST20009
• Direct-fit replacement reduces diagnostic and installation time

Compatibility

Designed as an OEM-style replacement hi-limit outlet sensor for LOCHINVAR hydronic boilers and water heaters. Cross-referenced as TST20009. Refer to your equipment service manual or LOCHINVAR technical support to confirm fitment for your specific model.

Installation Notes

Installation should be performed by a licensed plumber or hydronic heating technician familiar with LOCHINVAR equipment. Before servicing, shut off the gas supply, disconnect electrical power to the unit, and allow the system to cool to a safe handling temperature before removing the sensor. Consult the equipment service manual for the correct sensor port location and any required sealant or thread tape on the sensor fitting. Verify sensor resistance values with a multimeter after installation before returning the unit to service.

Technical Specifications

• Component Type: Hi-Limit Outlet Sensor
• Cross-Reference Part Number: TST20009

Standard Information

• Brand: LOCHINVAR
• Manufacturer Part Number: L100208544