It is designed to stay in the circuit continuously while the motor is energized to maintain the correct electrical phase shift

This hysteresis synchronous motor driven actuator features a one-handed removal mechanism

reducing mechanical stress on the combustion chamber and improving overall furnace reliability

When verifying HVAC motor specifications

which officially replaces 60M1001 and the Honeywell W7212A1033

Schneider Electric (Barber Colman) MK-6821 Proportional Control Els PW 17895 It is designed to stayThe Schneider Electric (Barber Colman) MK 6821 Proportional Control is a rugged 50 square inch pneumatic valve actuator engineered for precise linear movement in commercial HVAC systems. This spring return actuator operates on a 8 13 PSI pneumatic signal range, providing reliable fail safe positioning during pressure loss. Encased in a durable Nema 1 enclosure, it features a 1 8" NPT air connection and a 1" nominal stroke, making it a standard choice