McDonnell & Miller 63-M-HD Head Mechanism 30067439-890 This genuine OEM Lennox 47M55

This genuine OEM Lennox 47M55 combustion air booster is engineered to meet the exact static pressure requirements of G43UF

or condenser fan failure

ensuring accurate HVAC control linkage response across the full stroke of the motor

Common Questions & Technical Support What is the minimum pressure required for this valve to operate

this unit provides a stable 240V secondary output

McDonnell & Miller 63-M-HD Head Mechanism 30067439-890 This genuine OEM Lennox 47M55The McDonnell & Miller 63 M HD Head Mechanism (Part Number 143200) is a heavy duty replacement head mechanism designed for the Series 63 Low Water Cut Off. Engineered for both hot water and steam boilers, this manual reset mechanical control ensures critical safety by interrupting the electrical circuit to the burner in 15 psi steam or 50 psi water applications. It features a robust float operated design and includes the No. 2 M switch, providing