The red color-coded housing allows for immediate identification during field service

Confirm the oil sump depth and port size matches the 3 1/2-inch probe length and check the compressor nameplate for 120V heater compatibility

It typically functions as the power venter relay or fan relay

this Single Pole Single Throw (SPST) air pressure switch ensures that the inducer motor is generating sufficient draft before allowing the ignition sequence to proceed

Zonefirst SPRD-18 Damper Els PW 17895 The red color-coded housing allowsThe Zonefirst SPRD 18 is a professional grade 18 inch round barometric bypass damper engineered to maintain critical static pressure relief in multi zone HVAC applications. As zone dampers close, this single blade mechanical component automatically responds to rising pressure, diverting excess airflow to the return plenum or a dump zone to prevent coil icing and blower motor strain. Unlike motorized alternatives, the SPRD 18 utilizes a counter