Help on central heating motorised valve wiring

[terryplumb]

I suspect your issue is the wiring ,not the MPV.
More investigation required tomorrow !!
Good luck , do keep us posted.

 

[ericmark]

The DHW not required grey wire I have seen left disconnected many times either at the cylinder stat or the programmer and the user is unaware anything is wrong, as all it does is limit the DHW temperature to below the CH temperature, all still works.

The DHW is not electrically controlled by the motorised valve, if the valve is fully open then you get no DHW, but default with no power to valve is DHW. So if no DHW your not looking at the three port valve.

The valve has a bleeding lever, this without power moves the valve to centre position, and it can be latched in the centre position, when the micro switches fail, some times latching the valve will keep the central heating running, this was done with daughters house, and my son-in-law when cleaning knocked lever off latched position which resulted in CH failing, at of course most inopportune time, just when new baby arrived.

I was trying to test with the diagram you posted, which only shows one micro switch, so getting what seemed really odd results, new three port valve did cure it, but not helped by wrong answers to questions, did the radiator warm up in the summer when thermostat turned off got a no answer, in fact they did, just daughter did not notice.

As to Plumbers not doing electrics, yes the one I got here was the same, in fact even the central heating guy looked at my set up and said I can't sort out the electrics, lucky I could, but can understand why previous owners had given up and were burning wood for heating.

 

[Stevehobbs]

I suspect your issue is the wiring ,not the MPV.
More investigation required tomorrow !!
Good luck , do keep us posted.

Hi Terry
quick update after a long day….
Heating only with white separated out had 240V so concluded must be motor head so replaced. Also had a nightmare of a job but had to run a wire up from HW off on programmer into attic and down to airing cupboard to terminal 2 on cylinder stat and grey to MPV. Time to try and new motor head worked fine but boiler permanently running even if all off ie still heating water HW on supply permanently, had checked wiring that many times that was fairly sure it must be a programmer issue. Bought a new programmer and all good now thankfully.

Thanks for all your help really appreciated

steve

 

[Stevehobbs]

Hi Terry
quick update after a long day….
Hot water only with white separated out had 240V so concluded must be motor head so replaced. Also had a nightmare of a job but had to run a wire up from HW off on programmer into attic and down to airing cupboard to terminal 2 on cylinder stat and grey to MPV. Time to try and new motor head worked fine but boiler permanently running even if all off ie still heating water HW on supply permanently, had checked wiring that many times that was fairly sure it must be a programmer issue. Bought a new programmer and all good now thankfully.

Thanks for all your help really appreciated

steve

 

[terryplumb]

Don't ya just love a happy ending

 

[Stevehobbs]

The DHW not required grey wire I have seen left disconnected many times either at the cylinder stat or the programmer and the user is unaware anything is wrong, as all it does is limit the DHW temperature to below the CH temperature, all still works.

The DHW is not electrically controlled by the motorised valve, if the valve is fully open then you get no DHW, but default with no power to valve is DHW. So if no DHW your not looking at the three port valve.

The valve has a bleeding lever, this without power moves the valve to centre position, and it can be latched in the centre position, when the micro switches fail, some times latching the valve will keep the central heating running, this was done with daughters house, and my son-in-law when cleaning knocked lever off latched position which resulted in CH failing, at of course most inopportune time, just when new baby arrived.

I was trying to test with the diagram you posted, which only shows one micro switch, so getting what seemed really odd results, new three port valve did cure it, but not helped by wrong answers to questions, did the radiator warm up in the summer when thermostat turned off got a no answer, in fact they did, just daughter did not notice.

As to Plumbers not doing electrics, yes the one I got here was the same, in fact even the central heating guy looked at my set up and said I can't sort out the electrics, lucky I could, but can understand why previous owners had given up and were burning wood for heating.

The DHW not required grey wire I have seen left disconnected many times either at the cylinder stat or the programmer and the user is unaware anything is wrong, as all it does is limit the DHW temperature to below the CH temperature, all still works.

The DHW is not electrically controlled by the motorised valve, if the valve is fully open then you get no DHW, but default with no power to valve is DHW. So if no DHW your not looking at the three port valve.

The valve has a bleeding lever, this without power moves the valve to centre position, and it can be latched in the centre position, when the micro switches fail, some times latching the valve will keep the central heating running, this was done with daughters house, and my son-in-law when cleaning knocked lever off latched position which resulted in CH failing, at of course most inopportune time, just when new baby arrived.

I was trying to test with the diagram you posted, which only shows one micro switch, so getting what seemed really odd results, new three port valve did cure it, but not helped by wrong answers to questions, did the radiator warm up in the summer when thermostat turned off got a no answer, in fact they did, just daughter did not notice.

As to Plumbers not doing electrics, yes the one I got here was the same, in fact even the central heating guy looked at my set up and said I can't sort out the electrics, lucky I could, but can understand why previous owners had given up and were burning wood for heating.

Thanks all sorted now , I sympathise my ”engineer” won’t do electrics , another engineer came out this morning and because the wires weren’t neatly in a line in a 10 way block would not touch and wanted £1k to rewire in a line or recommended ripping out the existing boiler not 12 months old and replacing with a combi for £3.5k . Good work if you can get it, in fact was quite rude saying I shouldn’t be messing with something I don’t understand. Like you I can follow simple circuit diagrams and logic. I declined and carried on and all working fine now after running a wire from HW off to grey and 2 on cylinder stat, replacing motor head on 3 port and also new programmer which was sending signals when off . I may put wires in a line if I get a spare hour over the weekend ….. Thanks for your help

 

[ericmark]

The main thing is to keep a record of how wired, this is mine, yes I know not correct should have two relays, but once written out like this one can follow it and find the errors.