When using a 3-port valve, the control system may be known as a Sundial Y Plan system or a Honeywell Y Plan system. lt;p>Honeywell 22mm Mid-Position Valve is designed to be used in conjunction with a room thermostat and cylinder thermostat to provide full temperature control of a conventional, fully pumped central heating installation. The valve has been designed to control the flow of water in domestic central heating systems, where both radiator and hot water cylinder circuits are pumped. The Honeywell V4073A Mid Position Valve is typically suited for small to medium sized installations.</p>

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.

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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 Honeywell motorised valve faults detailed above are likely to apply to most domestic Honeywell valves. However, if you need to replace the motor it may be easier to remove the powerhead so you can work on it in the open. Remember, on early Honeywell motorised valves (pre-1985) you can’t remove the powerhead without draining down first! I reconnect the power and all the same with motor lever as described in step 3. NB yesterday at this point the valve motor was turning at this point even though controller said off (mind you, hw yesterday was on constant ON but don't believe that would have switched on the motor anyway).

The pump is going all the time, trying to do something and the pipework is throbbing! But is it pumping water? 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 Honeywell valves have a D-shaped top to the spindle but you can also use a spanner on this. If you do this, you must use very little force as it is very easy to shear a spindle or damage the valve internally.A normally-open valve is open when no power is being applied to it and needs electrical power to drive it closed. 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! 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) We find it is normally about 2.1kΩ (2100 ohms) if the motor is cold and up to 2.4kΩ (2400 ohms) if the motor is quite warm. I think that a reading anywhere between 2.0kΩ (2000 ohms) and 2.5kΩ (2500 ohms) suggests that the motor windings are probably OK. If the reading is many times higher than that, or it is open circuit, the motor has failed.