Replacement Synchronous Motor for motorised valves ACL Honeywell Landis Gye Satchwell Sopec Tower DIY Replacement 2-Port 3-Port Valve Failure

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With the mains electrical supply turned off and isolated, the resistance across the two motor wires (either both blue or both orange) can be tested.

Unless the valve is very old (pre-1985) it should be possible to remove the powerhead from the valve body without draining down. Replacing a failed Synchron motor in a Honeywell motorised valve is quite straightforward, assuming you know how to work with mains electricity safely. Apart from the few moments when it is switching between ports, Port A and Port B are not open together.In the past, Honeywell told us that the motors made for them produced a higher level or torque than the standard SYNCHRON motor. Much of what we describe also applies to ACL Drayton motorised valves like the Drayton 2-port ZA5/679-2 22mm zone valve and the Drayton 3-port MA1/679 22mm mid-position valve. This should have left you with a failed motor which is now disconnected from the powerhead and can be discarded. When the valve is fully open, the end switch closes, allowing electrical current to pass from the grey wire to the orange wire and from there to the boiler Switched Live.

The electronics in Honeywell motorised valves tend to be quite stable and show relatively few faults but the motor may fail after years of operation. On more recent valves, one wire is joined with a crimp and the other is wired directly to the electrical components of the valve.The powerhead contains the motor, which is used to drive the valve open, and an auxiliary switch or end switch. I was told by the Honeywell technical guy on an official Honeywell course 25 years ago that the quality replacement motor had blue wires and is heavy duty. Once the cover is back in place, the power can be re-instated and the operation of the motorised valve can be tested. When the cylinder is up to temperature, the hot water motorised valve closes and no longer tells the boiler to fire, so the heating now stops too.