Honeywell Sundial y plan 3 position diverter valve ?

Honeywell Sundial y plan 3 position diverter valve ?
I am having problems with my Honeywell Sundial y plan 3 position diverter valve. I bought a replaceent synchron motor but although the original motor was faulty this did not cure the problem. I think the actual valve needs looking at. I have now manually pushed the leaver over on the valve in order to run both the HW and CH from the HW side of the electronic controler. I was only able to push the lever over and latch it with the motor unattached. Do I have to drain the system in order to take the valve off? Can you freeze the pipes? or could this be the micro switch on the valve?

I dont know what your problem is.

On all but the oldest valves the head only can be replaced on its own.

Fairly obviously to replace the whole valve the system has to be drained or could be frozen if you can freeze three pipes at the same time!

Tony

I think you need to establish that the valve does move to CH only position.
If the wiring is correct (no reason why it should not be ) and the valve spindle is not stiff (could remove head and test ), the valve should move to CH only position. If it does, then the micro switch that feeds power to the boiler to light it will have failed.
If the valve does not move to CH only position, then you have to suspect wiring, stiff spindle. Valve motor/micro switch.
Quite often a failed micro switch No2 is the cause of the boiler failing to light, even though the valve has moved correctly.
Micro switch No1 feeds power to the motor from the grey wire, so if this switch fails the valve can not move beyond mid position.
Changing the motor is about the only DIY job you can do without difficulty but does not always solve the problem, so replacing the valve head is a better option if it can be done and you don't need to drain down to change the head.
So back to original question! Does valve move first to mid position and secondly does it move to CH position.?