The Lennox H5891 is an OEM-replacement resettable high-limit switch engineered to protect your pellet stove from dangerous overtemperature conditions. When the firebox or exhaust pathway exceeds a safe operating threshold, this switch interrupts the pellet feed automatically -- preventing damage to the stove and reducing fire risk. Sold under part numbers H5891 and 20160 (also cross-referenced as NBK Parts 20160).
Pellet stoves rely on high-limit switches as a last line of defense against runaway combustion. If a clinker blocks airflow, an auger jams, or the exhaust system becomes restricted, heat can build rapidly inside the stove. The H5891 detects that spike and cuts power to the auger motor and/or igniter circuit, stopping fresh pellets from feeding into the burn pot until the problem is resolved and the switch is manually reset.
This is a direct OEM-specification replacement -- not an aftermarket approximation. Using the correct Lennox-specified switch ensures the trip temperature and reset characteristics match what the stove's control board expects, keeping your warranty-era repair or long-term maintenance accurate.
Manual reset after the stove cools. No need to replace the switch after a single overheat event -- inspect the cause, correct it, and reset.
Interrupts the auger/pellet-feed circuit when the stove temperature exceeds the rated threshold, preventing fuel buildup during an overheat condition.
Confirmed fit for Lennox Bella, Winslow PI40, and Winslow PS40 pellet stove models. OEM part number H5891, also sold as NBK 20160.
Weighs approximately 0.1 lb. Easy to handle during service. Typically mounts near the heat exchanger or exhaust plenum inside the stove cabinet.
The high-limit switch is a normally-closed (NC) thermal device wired in series with the stove's control circuit. Under normal operating temperatures it passes current freely. When the sensed temperature rises above the rated trip point, the bimetal element inside the switch opens the circuit -- immediately halting the auger motor that feeds pellets into the burn pot.
Once the stove has cooled to a safe temperature, you press the small reset button on the switch body to restore continuity. The stove will not restart until this reset is performed, which forces the operator to investigate and correct the root cause before returning the stove to service.
Before installing a replacement switch, it is worth identifying why the original tripped. Common causes include:
The Lennox H5891 / part 20160 is confirmed to fit the following Lennox pellet stove models:
High-limit switch replacement on Lennox Winslow and Bella series stoves is a serviceable DIY task for owners comfortable with basic appliance repair. General steps: