This ensures your heating system only fires when the exhaust path is clear and stable

the diaphragm and housing assembly can typically withstand a maximum surge of 30 psi

Standardized Dimensions: Precise fit at 20x13x3/8 ensures no air bypass

System Compatibility: Explicitly designed for McDonnell & Miller RS sensors used in remote level sensing configurations

the internal bimetal disc in the switch may have fatigued

Williams P500406 Limit Switch This ensures your heating systemThe Williams P500406 Limit Switch is a critical safety component designed for precise thermal regulation in Williams Monterey top vent heaters and furnace gas valves. Engineered with a 270 degree Fahrenheit Cut Out, this Manual Reset (M R) limit switch serves as a reliable failsafe, interrupting the electrical circuit to the gas valve if internal temperatures exceed safe operating parameters. This specific HVAC high limit control is essential for