Honeywell V4073A1039/U 22 mm Mid Position Valve

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If it’s the other way round, and the 2-port valve controlling the hot water circuit is failing, it may be less obvious. The heating circuit valve may be open for long periods telling the boiler to fire. If the hot water valve is partially open, you may not run out of hot water. Replacement Honeywell SYNCHRON motors are available but are a bit more expensive. For a long time we’ve used the standard SYNCHRON motors as replacements, with very few problems. Some micro switches are required to work which have failed along with the motor, and they are required to work to indicate to boiler the valve has opened. Only when both white and grey wires are energised (and the valve goes to the Heating Only position) can the orange wire get its 230V supply via the valve itself. (Remember, the orange wire can also get 230V from the cylinder stat if it is calling and a hot water program is on.)

But then I go confused because I was wondering why it was opening the valve in the first place when the controller hasn't asked it to do so. The motor in the valve has failed ( but why doesn't the manual open cause flow and the boiler to fire up ? ) The Y Plan and S Plan names are more commonly used when other Honeywell controls are also used (programmer, room thermostat, cylinder thermostat and wiring centre). The wires to disconnect are the two wires which run from the motor. On earlier motorised valves, these were both joined to other wires using metal crimps encased in plastic. On more recent valves, one wire is joined with a crimp and the other is wired directly to the electrical components of the valve. My first thought was that the boiler wasn't firing up because the micro switch(es) to do so were faulty.System boilers may also have a diverter valve or zone valve built into them and might not have any external zone valves.

Synchron valve motors can remain energised and hot for many hours a day, all through the winter. They may eventually fail. A failed Synchron valve motor will prevent a 2-port motorised valve from working. The valve won’t be driven open and the end switch will not be made (connected) so power will not be sent on to the boiler or pump. A programmer and cylinder thermostat (stat) are used to control the times when the hot water is heated and to control the maximum temperature of the stored hot water. There is, however, more information the lever can give us if we know what we’re looking for. The lever pushes the valve open against the return spring. The valve does not pull the lever over towards the open end as the valve opens.

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Crimps are metal tubes within plastic insulation, which are flattened using pliers to trap two wires, joining them electrically. These crimps can sometimes be re-opened by using pliers to squeeze together the edges of the flattened tube. This can be done with the plastic in place. If successful it frees the two wires. The plastic insulation may break, in which case the crimp is discarded. Where two 2-port motorised valves are fitted (one for the heating circuit and one for the hot water cylinder circuit) the fault may be disguised. Even though one valve only partly opens itself and is unable to fire the boiler, the valve on the other circuit can open fully and fire the boiler. The pump then pushes heated boiler water through both the open valve and the partially open valve. A programmer and room thermostat (stat) are used to control heating times and room air temperatures. The programmer and room stat may be combined into a single programmable room stat. When Heating is also called for, the white wire is energised and the valve will motor to, and stop in, a mid-position. Power for the boiler is still supplied directly from the cylinder thermostat. The orange valve wire may have a potential of 230V but this is coming from the cylinder stat (to which the orange wire is also connected) and not from the circuitry of the valve.

A normally-open valve is open when no power is being applied to it and needs electrical power to drive it closed. Think I had this before but switched itself off after some time, do currently waiting to see what happens. Also need to test with hot water on constant. We are currently using Royal Mail Parcelforce and DPD as our delivery providers, all small items will be delivered by Royal Mail, these can take up to three working days to reach you. Sometimes if I bang the valve with my hand sometimes CH and HW start to work after some gurgling noises Whereas the internal electrics of the 2-port valve are quite simple, the internal electrical controls of the V4073A mid-position valve are more complex.Occasionally we come across a Honeywell motorised valve where the powerhead jams but the spindle (actuator shaft) is still free. Where this happens it is usually with the valve jammed open. If all the power to the central heating system is turned off, and the manual lever is still loose across the whole slot, the mechanism may be jammed.

The Honeywell V4073A 3-port valve has five wires. These are blue, green/yellow, white, grey and orange. Note that the grey and orange wires are used differently from the grey and orange wires of the 2-port valve!V4044C motorised valves are 3 port diverter valves. They send flow to either the hot water port or the heating port but not both, except briefly during switchover. They are 3 wire valves. Sometimes a powerhead is able to drive the valve only part way open but not far enough for the auxiliary circuit end switch to close. This valve will then not be able to tell the boiler to fire. The Honeywell V4073A is a spring-return valve. Port A or port B can be closed by a rubber ball, though never both at the same time. The rubber ball is moved between ports A and B by an actuator shaft or spindle which is driven by the powerhead. The inlet port AB can never be closed; the ball only moves between port A and port B.