How to Replace a Honeywell Synchron Motor

Honeywell Synchron motors open and close motorized Honeywell zone valves in hot water heating systems that utilize radiators.
Synchron motors actuate zone valves that control the hot water flow to radiators.Synchron motors actuate zone valves that control the hot water flow to radiators.
These valves are signaled by the thermostat in a zone, to admit or limit the flow of hot water to the radiator. A typical indication of a defective zone valve motor is failure to respond to the signal from the thermostat. Manually actuating the spring-loaded valve lever will indicate no binding or mechanical defect, and tests with a multimeter will verify that the valve motor is receiving 24-volt power. Synchron motors in Honeywell zone valves are replaceable without draining the water from the system.

Step 1

Turn off electrical power to the heating system, at the breaker box.

Step 2

Remove the valve cover.

Step 3

Unscrew the single screw that secures the motor unit to the valve body.

Step 4

Push the valve's manual actuating lever -- located on the end of the valve below the power wire connector -- into the "Open" position, and hold it there.

Step 5

Lift the motor unit up and away from the valve body. Release the manual actuating lever, and allow the valve to spring back into the "Closed" position.

Step 6

Cut the two wires leading from the motor to the plastic terminal connector. Leave enough existing wire at the connector to splice the new motor wires. Strip one-half inch of insulation from the ends of both wires.

Step 7

Push the valve's manual actuating lever -- located on the end of the valve below the power wire connector -- into the "Open" position, and hold it there. Install the new motor unit into the valve body. Insert the single mounting screw and tighten. Release the manual actuating lever, and allow the valve to spring back into the "Closed" position.

Step 8

Splice the two wires from the motor to the two existing wires, using the supplied screw-on connectors.

Step 9

Replace the valve cover. Restore power to the system, at the breaker box. Test the action of the valve by adjusting the thermostat to call for heat.

Things You Will Need

  • Slot screwdriver
  • Wire cutters
  • Wire strippers

About the Author

Gus Stephens has written about aviation, automotive and home technology for 15 years. His articles have appeared in major print outlets such as "Popular Mechanics" and "Invention & Technology." Along the way, Gus earned a Bachelor of Arts in communications. If it flies, drives or just sits on your desk and blinks, he's probably fixed it.