Heating only on using manual lever on motorised valve

[azbij]

Hi, I'm trying to work out why my Y-Plan heating system is not behaving as expected.

HW works fine. CH will only work if I manually move the lever on the 3 port motorised valve.

I thought this was a problem with the synchron motor, but a replacement has not made any difference.

The steps I have taken and my findings:

• Power down whole system to reset (not just at controller)
• Set HW cylinder thermostat to MIN. This gives continuity across Common and #2 (when I set to max continuity is between common and #1)
  
• I have unwired the room thermostat and hard-wired terminals 1 and 3 as per instructions of wiring centre
• On controller, I set HW and CH to ON. Checked that there is 240V at wiring centre for HW and CH
• Synchron motor does not move; boiler does not come on
  
• Checked terminals to/from motorised valve at wiring centre - grey and white=240V, orange- nothing.
• Across synchron motor - seems to be 100V AC or 50V AC depending on which connections I connect red/black to
  
• If I move the manual lever on the motorised valve, the microswitch clicks, the boiler fires up. The valve is open for CH and radiators warm up. The orange wire between wiring centre and motorised valve is now live. No crunching of gears heard whilst lever is moved.

The synchron motor worked before I put it in the motorised valve - at 240V, turning slowly.
If the 3 port valve were jammed, surely I wouldn't be able to open it using the manual lever

I'm stumped so any help would be appreciated!

thanks,
Andrew

wiring centre is Honeywell 42005748-001; Honeywell 3 port motorised valve

 

[Dean744PiN5]

If you have 240 going In To the vaalve but not coming out and you have changed the synchronous motor then you need to change the whole valve, sometimes the mechanicals wear and wont make the micro switch, or the spindle is stiff.

 

[azbij]

thanks, Dean

Although there is 240V to the valve, there is only 100V to the motor. I understand the electronics in the valve head are supposed to change shape of the AC supply to the motor but is that expected? The motor is marked as a 240V motor. The switches are working in the vavle head but maybe it's worth replacing the head in case the electronics have given up?

As one last test, I tried disengaging the synchron motor from the underlying valve to check whether the motor was turing but not managing to turn the valve due to high resistance. Result is that the motor did not turn even when the motor spindle was just in the air, not engaged with anything.

cheers,
Andrew

 

[azbij]

It looks like the problem must have been with the electronics in the actuator.

I bought a new actuator and fitted it and heating is working fine now.