Williams P151800 Gasket The most common sign is

The most common sign is the furnace lighting for 2-5 seconds and then immediately shutting down

and Series 221 make-up feeders

What causes the 320-degree rollout switch to trip on a York furnace

it is standard practice to hand-secure the four bolts and then tighten them to approximately 16 ft/lbs to ensure an even seal across the valve assembly

Williams P151800 Gasket The most common sign isThe Williams P151800 Gasket is a critical OEM replacement component engineered for high performance sealing within Williams Forsaire Direct Vent wall furnaces. Specifically designed as a pilot tube gasket, this part ensures an airtight seal at the control assembly interface, preventing combustion air leakage and maintaining precise manifold pressure. This gasket is compatible with several Williams furnace series, including the 4007, 5507, and 6007