Honeywell V4073A1039/U 22 mm Mid Position Valve

Product Information

When using a 3-port valve, the control system may be known as a Sundial Y Plan system or a Honeywell Y Plan system. The auxiliary circuit allows several 2-port motorised valves to be used to control separate zones without interacting electrically. Otherwise, if several zone valves were used without auxiliary circuits, and all were connected to the same pump so that the Live wire that opened each valve also fed the pump Live, there would be problems.

The V4073A 3-port valve never closes water flow through the valve completely. There is always an open pathway from port AB to port A or from port AB to port B or from port AB to both ports A and B at the same time.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. 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 normally-closed valve is closed when no power is being applied to it and needs electrical power to drive it open.I tried out of interest to see what would happen during this state, if I set the controller to switch on heating. Nothing happened.

Started writing this and after some time the bloody boiler has now started. Radiators now getting warm. Typical!!! In larger properties, 28mm valves may be used (the 5-wire 3-port V4073A1088 and the 6-wire 2-port V4043H1106). The 28mm V4043H1106 2-port zone valve has a6 th wire, coloured white. This white wire might not be used. In that case it should be made safe electrically. V4043H1106 is a 2 port, 28mm compression, 6-wire, normally-closed zone valve with an auxiliary end switch 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. If you are able to do so safely, you could try disconnecting and isolating safely the white wire from the motorised valve, and see if the valve moves then when the power is restored. If it doesn't move the problem is with the external wiring, in that the white wire is being energised from somewhere when it shouldn't be.

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Secondly, as the solution is to replace part or all of the valve head, is this model one that doesn't require draining of the water. How can I tell? Valve is in a bit of an awkward position in the airing cupboard so would rather not take the chance.

The pump has failed, and is pretending to be working ( but then why does banging the valve cause everything to work sometimes ? ) System boilers may also have a diverter valve or zone valve built into them and might not have any external zone valves. 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.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. 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. V4043H1007 is a 2 port, ¾” BSP Female threaded, 5-wire, normally-closed zone valve with an auxiliary end switch When the programmer and stat send a Live feed to the 2-port motorised brown wire, the motor drives the valve open to allow water to pass. 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. Unless the boiler thermostat is already up to temperature, the boiler will now fire.