Honeywell V4073A1039/U 22 mm Mid Position Valve

Product Information

A normally-closed valve is closed when no power is being applied to it and needs electrical power to drive it open.

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 all electrical power to the heating controls is switched off, the spring pulls the ball across to close port A, leaving port B open. This is the relaxed state or de-energised state of the valve. It is also sometimes called the Normal state. The commonest fault with Honeywell motorised valves is motor failure. Honeywell valve motor fault? Testing a Synchron valve motor 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. A failed motor will prevent the motorised valve from opening but it is not the only cause of a valve failing to open correctly. After years of use, the O rings sealing the valve spindle (or actuator shaft) can fail. When this happens, central heating water will seep past and will corrode the metals.If Hot Water is then satisfied (either by the programmer or cylinder stat), the grey wire is energised. As there is still a demand for Heating, the valve will motor to the Heating Only position (port A open; port B closed) and switch a 230V supply onto the orange wire, to power the boiler. In smaller properties there is usually one programmer which has two channels. One programmer channel controls the heating (radiators or underfloor) and the other programmer channel controls hot water. Where additional zone valves are used there will usually be another programmer or timer. Honeywell motorised valve construction Honeywell say that the manual lever located on the end of the powerhead is not a position indicator and should be used used for filling the system and for draining down only.

If I move the lever to manual open position, nothing happens, neither CH or HW pipes from valve become hot and boiler does not fire. Does this suggest that the valve mechanism is not opening?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).

In medium sized or larger properties, using a combi boiler, there may be an additional zone valve external to the boiler which allows the heating to be split into two zones. The pump is going all the time, trying to do something and the pipework is throbbing! But is it pumping water? The V4043B valves are uncommon and likely to be found in solid fuel systems. These valves fail-safe in the open position in the event of a power failure or valve motor failure. Slide the blunt end of the motor sideways until the flange comes out from the tab holding it down. This can be a bit of a fiddle. The motor then comes free of the valve, held only by the two wires which connect it electrically. These two wires may be blue (in a Honeywell original Synchron motor) or orange (most replacement Synchron motors).

Started writing this and after some time the bloody boiler has now started. Radiators now getting warm. Typical!!! I tried out of interest to see what would happen during this state, if I set the controller to switch on heating. Nothing happened. 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.) If the valve motor fails, the motorised valve will not open. The valve will not then close the end switch and so will not complete the auxiliary circuit. The boiler will not fire (with no open pipe circuit to dissipate the heat), unless another motorised valve opens another pipe circuit and calls the boiler into action. This prevents the boiler firing and the pump running when there is no water circuit open.