meaning the circuit completes only when the 24V coil is energized

Always provide a drip loop in the capillary to prevent moisture from reaching the switch and avoid sharp bends that could compromise the liquid-fill charge

providing a mechanical failsafe and accurate temperature sensing without the need for external power logic

typically at the edge of the 0

For contractors managing building automation systems (BAS) or legacy pneumatic control loops

Fenwal 35-655910-991 Module Els PW 17895 meaning the circuit completes onlyThe Fenwal 35 655910 991 is a robust 24 VAC Hot Surface Ignition (HSI) control module engineered for precise sequencing in gas fired furnaces, boilers, and commercial heating equipment. This micro processor based control manages the combustion blower, ignitor, and gas valve while providing continuous flame monitoring. Designed for field replacement and OEM applications, it features a 45 second prepurge and interpurge cycle to ensure the combustion