The -800 Bill of Material (BOM) highlights its readiness for the field

specific twinning capabilities depend on the furnace model

preventing motor burnout and improving longevity

The Air Over motor housing is designed to be cooled by the fan's own airflow

Operating on a 0(2) to 10 VDC or 0(4) to 20 mA proportional control signal

Tjernlund Products PS1503 Switch 322027-701 The -800 Bill of MaterialThe Tjernlund Products PS1503 is a high sensitivity duct pressure switch engineered to automate HVAC accessories by detecting positive air pressure within the supply plenum or trunk lines. As the direct replacement for DFS 221 227, this SPST normally open switch simplifies field installations by eliminating the need for complex interlock wiring with the furnace blower. The PS1503 duct airstat features a snap acting mechanism triggered by a precise