Is the manual lever directly connected to the spindle? If so if I move it to open position then water must flow and therefore the boiler should fire up as hot water leaves it. The electronics in Honeywell motorised valves tend to be quite stable and show relatively few faults but the motor may fail after years of operation. Honeywell use Synchron motors and these are freely available but there are lots of cheap cloned motors out there. These look identical but, instead of the name SYNCHRON, they use the word Synchronous.

I tried out of interest to see what would happen during this state, if I set the controller to switch on heating. Nothing happened. If the powerhead was removed from the valve to make it easier to change the motor, it must now be re-attached to the valve. The power head cover can then be refitted and secured with the single screw. Make sure it sits squarely on the powerhead, with no wires pushing out from the sides. Much of what we describe also applies to ACL Drayton motorised valves like the Drayton 2-port ZA5/679-2 22mm zone valve and the Drayton 3-port MA1/679 22mm mid-position valve. Iflo motorised valves and British Gas motorised valves have similar faults. It may also apply to the Tower VAL222MV motorised valve, the Siemens CZV222 motorised valve and the Flomasta 27900SX motorised valve. 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. When the valve is working should the lever move over to the open position when it is doing HW or CH?Honeywell make a large range of motorised valves used in domestic central heating systems. The most common by far are the 22mm 3-port, 5-wire, mid-position valve and the 22mm 2-port, 5-wire, zone valve. These 22mm valves (3-port V4073A1039 and 2-port V4043H1056) are used in smaller and medium sized properties. 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! My first thought was that the boiler wasn't firing up because the micro switch(es) to do so were faulty. Drive spindle of a Honeywell motorised valve. It is accessed by removing the valve powerhead. Be warned, with Honeywell motorised valves made pre-1985 you have to drain down first to remove the powerhead!

When a V4073A mid-position valve is set up in a Y-Plan configuration and Hot Water is called for, power to the boiler is provided directly from the cylinder thermostat. The valve is not energised.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. 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.

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. When a demand comes from the programmer (via the thermostat), the motor is energised and drives the valve open to allow water to pass. When the valve is fully open, a microswitch is operated in the powerhead, connecting the grey wire to the orange wire. This is called closing the switch. It sounds a bit counter-intuitive, but when a switch is closed it is completing the circuit and allowing current to pass; when the switch is opened it is opening a break in the circuit and stops current from passing. Both of these genuine SYNCHRON motors work in Honeywell motorised valves. The motors SYNCHRON make specifically for Honeywell come with two blue wires There are lots of poor quality synchronous motors out there. If the motor cap says “Synchronous” rather than “SYNCHRON ®” it may cost less than half but you’ll probably be changing it again before long!

It will make it easier when re-fitting it (just remember which end the flex was connected or take a picture on your phone). The powerhead can only fit one way round onto the valve body but if space is tight that might not be obvious. Honeywell V4073A1039 22mm 3-port mid-position diverter valve. These are 5-wire valves. When used with other Honeywell controls the setup is know as Y Plan With the valve at rest (power off) it sits in the hot water only position. When the heating is required, a live on the motorised valve's white wire (from the room thermostat) winds it to the first microswitch (SW1) where if the hot water is also required, it will stop. At this point the valve is in the centre position. If the hot water isn't required, it will continue on past the first microswitch (SW1) to the second microswitch (SW2) which should start the boiler. At this point the valve is at the end of its travel in the heating only position. As I understand it there are some micro switches in the valve, if they are not operating correctly, does the boiler think that the valve has not opened and therefore does not fire up?