Common indicators include the ignitor glowing faintly without igniting the gas

This OEM Lennox replacement part

Exact Geometry: Featured 70-degree sensor bend and 1-7/8 inch extension length ensures the rod is positioned perfectly within the burner flame for rapid detection

or visible bulging on the capacitor casing

Honeywell T822K1000 Thermostat Common indicators include the ignitorAs an HVAC professional, you know the value of a dependable, "no frills" mechanical control for standard 24V heating systems. The Honeywell T822K1000 is an industry standard, non programmable low voltage thermostat designed specifically for 1 heat only applications. This vertical mount thermostat features a precision snap action switch and a bimetal sensor element, providing high reliability for gas, oil, or electric heat systems, as well as heat pump