Honeywell Motorised Valve Problems

V4073A Synchron motor reliability modification

V4073 modification V4073 modification V4073 parts
Valve with cover and Synchron motor cover removed. This example has already had the motor replaced. No vents, and hence zero air circulation, results in the fully enclosed motor windings overheating during sustained power periods. Ultimately this can lead to an open-circuit motor winding. Note the crude but effective lower right fixing slot for the motor lug. The opposite (screw) fixing is behind, top left.
 Motor and valve covers can be drilled for cooling. Be sure to fully deburr the holes prior to reassembly. Whilst it would be difficult to poke anthing in these holes, if this idea is adopted, it would be preferable to drill a greater number of smaller diameter holes (3-4mm) in the valve cover.
Motor cover fitted V4073 modified Synchron motor
Modified motor cover clipped back into place. Completed valve. Replacement Synchron motor assemblies (incorporating the gearbox) are readily available for under £10.


Warm radiators with Central Heating off ?  Your balls gone hard...!

Hardened ball Ball Kit
Hardened ball after several years subjected to hot water. Crazing of the rubber surface is just visible; the ball can also deform from spherical with age. This prevents the ball sealing against pump flow when only the Hot Water is heating. The symptom is that the radiators begin to warm-up when the CH is supposed to be off.
The remedy requires the fitting of a repair kit after electrical isolation of the system and a partial drain-down to a level below the zone valve.
 The Honeywell repair kit, 40003918-007 for the V4073A, resolves this problem with a complete new ball plate and 'O'ring seal. The entire motor head is retained by two screws accesed after removal of the cover. The ball plate is retained by four bolts - note that two double as threaded pillars for the valve head fixing screws. Carefully remove the old seal and clean off any deposits around the inner housing ball seats and valve body. Be careful not to scratch or score the seal and ball seat faces in the brass valve body. Reassemble using a smear of waterproof grease (e.g. Castrol LM) on the seal.
This problen can also affect other valves but different repair kits are required e.g. the V4043C/V4043H  2-port valves require Honeywell repair kit 40003918-006. BES Ltd are stockists.
Note that very early Honeywell valves require a powerhead conversion as well and it is more economic to replace the entire valve!

The Horstmann Z322XL 3-port and Z222XL 2-port valves use a reinforced plastic motor housing which does not conduct the heat from the valve body to the same degree. The motor housing cover is also incorporates a ventilation grill to keep the motor cooler during operation and they have a 5-year manufacturer guarantee. They are electrically and physically identical from an installation perspective.

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Last updated 01/01/07