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. Starting with the controls set for Heating Only, hold the lever tight against the right side of the slot. Now get someone to select Hot Water too, so you get Heating and Hot Water together. You may need to turn the cylinder stat up to make it call. As soon as Hot Water is also called, you will hearthe valve start to unwind under the force of the spring, then you will feel the lever “bump” your finger. Honeywell 2-port motorised zone valves (V4043H) are electrically quite simple. The powerhead contains the motor, which is used to drive the valve open, and an auxiliary switch or end switch. Honeywell 22mm zone valve operation (V4043H1056) 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. 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 Honeywell motorised valve faults detailed above are likely to apply to most domestic Honeywell valves. Replacing a failed Synchron motor in a Honeywell motorised valve is quite straightforward, assuming you know how to work with mains electricity safely. Make sure you read the whole process through before starting!

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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. The powerhead or actuator is the electrical section. It’s comprised of a motor and some electronic components and usually has one or more microswitches.

You should be able to feel a bit of spring resistance, right at the far end (Man Open end) of the slot. This can cause the valve spindle to seize. It often becomes stiff to turn at first and the valve may give intermittent problems. Eventually, the spindle may become so stiff that the valve motor cannot turn it at all.On older style valves pre-1985, which do not have the replaceable head feature, the adaptor plate assembly can be used to upgrade the valves, to allow the replaceable powerhead to be used.” 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. 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.