this push-button HVAC controller is specifically designed with a dual relay type that supports sequencing relays

the A19AAB-4 is designed with a fixed 3

the FUS0823 is the direct replacement for S8402-091

Is this compatible with LP or Natural Gas systems

Disconnect power and use a multimeter to check the resistance across the leads

Reznor 177633 Pressure Switch Els PW 17895 this push-button HVAC controller isThe Reznor 177633 Pressure Switch is a critical OEM replacement part designed for precision monitoring within commercial gas heating systems. Engineered for unit heaters and duct furnaces, this combustion air pressure switch kit is factory calibrated to a 0. 50" W. C. setpoint (water column). The Reznor 177633 ensures safe ignition sequences and reliable venting verification by detecting proper differential pressure before allowing the gas valve to