Hot water issue / Motorised Valve

[DanV8]

Evening all, hoping someone can shed some light on this issue. Heating works fine, though as soon as you turn on the hot water, it shuts the boiler off. Turn it off and the boiler comes back on. The motorised valve body turns freely by hand with valve head taken off and if placed in hot water position manually I can direct the flow to the tank, I have fitted a new 3 way Valve head ( Honeywell V073a) and can hear the valve operate when I turn on hot water, though of course as boiler shuts off I have no hot water. The system is oil fired with a hot water tank. Any help greatly appreciated, I’m thinking it’s to do with the micro switches in the head maybe..any help greatly appreciated. Cheers

 

[SimonG]

Did you change the head before you had this problem or did you change the head to try and fix the problem?

 

[DanV8]

Hi, there was the issue originally in that there was no hot water at all, though not because boiler wasn’t firing. Hence replaced the head with a cheaper aftermarket p, that worked for around 5 weeks and failed. So replaced with a Honeywell as per original, now the current issue. Made sure wires where correct in each change and that the valve moved freely. The fact I can here the valve move when I switch it to hot water makes me think the micro switch is the issue, but seems odd as it is brand new hence wondered if I’m missing something. Thanks

 

[SJB060685]

Dodgy cylinder stat im guessing. During CH and HW the cylinder stat sends live to boiler. When in CH mode its done through the second switch.

 

[DanV8]

Dodgy cylinder stat im guessing. During CH and HW the cylinder stat sends live to boiler. When in CH mode its done through the second switch.

Cheers for that, I did consider that and tried adjusting it to see if that worked in any other position, though you could be right in that it is completely dead, that would make sense I guess. Thanks

 

[SJB060685]

Cheers for that, I did consider that and tried adjusting it to see if that worked in any other position, though you could be right in that it is completely dead, that would make sense I guess. Thanks

A multimeter will prove me right or wrong. If I'm right you will have no feed from cylinder stat demand regardless of the temperature adjustment.

 

[DanV8]

A multimeter will prove me right or wrong. If I'm right you will have no feed from cylinder stat demand regardless of the temperature adjustment.

Thanks I will test in the morning, I have just tried moving the tank stat around with it clicking on and off and no difference to the system. This makes me think I wonder if the cable has been tightened on insulation maybe when fitted the new valve head, or it could of course be coincidence that has failed aswell. I’ll check the feed in the morning and update. Thanks for your help.
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Just to update on this, did further investigating with my meter and wiring diagram this morning, found the problem. It was terminal 6 (NO) in the programmer that the cable had snapped in the terminal. Hence now all sorted. Cheers