Heating turning on and off with hot water stat

[Bobthebuilder95]

Had another tread which described other issues. However I have now condensed the issues into one strange one, which I can't find any other examples of online!

Essentially with the heating on and hot water off if the hot water cylinder thermostat is turned up the heating will stay on full power irregardless of the room thermostat.

However with the cylinder stat turned to mininum the heating will function exactly as intended clicking on and off to maintain the temperature set on the room stat.

In summary the hot water stat directly effects the heating despite the hot water being turned off at the programmer.

Any help appreciated as it is driving me crazy!!

 

[ianmcd]

you have already been told it is wired incorrectly

 

[Bobthebuilder95]

Thanks for the reply, does my description help narrow down the wiring issue?

 

[Bobthebuilder95]

Just read on the honeywell wiring centre pdf that if a 2 chanel programmer is used make sure terminal 1 is cut, it currently is not and a 2 channel programmer is being used.

Could this be causing all the issue?

 

[stem]

Probably. I'm not sure exactly how the link is connected internally to the wiring centre, but it will no doubt somehow connect the 'Heating' & 'Hot Water' on circuits together so that they can both be controlled by a single channel programmer, which would explain why the hot water control circuit remains live when it should be switched off. (because it's still connected to the heating via the link)

Then you could end up with a live on the motorised valve's grey wire (programmer = hot water off) so the valve ends up in the heating only position where it wouldn't normally run the boiler if the white wire wasn't live from the room stat, so nothing would happen. However, because of the cylinder thermostat is still powered that runs the boiler instead. Meanwhile the water never gets hot enough to switch it off because the valve is in the heating only position, so the radiators just keep on going....

 

[Bobthebuilder95]

Hi all, just for closure I cut link one and now all is working exactly as it should.

Thanks

 

[stem]

Well done in spotting the uncut link . Sorry I suggested in your other thread that you had been tinkering with the wiring. I could see there was obviously some incorrect wiring rather than the failure of a component....and wires don't move on their own.

When you said "Recently had boiler fixed, new fan, in our new house. Tonight I noticed it was very hot even with thermostat down low, checked and the boiler was still on" it gave me the impression that the problem had only just occurred, hence my conclusion of someone 'tinkering' with the wiring but in reality it would have been there from the original installation. Can't believe that whoever commissioned the system failed to notice it.

 

[Bobthebuilder95]

Well done in spotting the uncut link . Sorry I suggested in your other thread that you had been tinkering with the wiring. I could see there was obviously some incorrect wiring rather than the failure of a component....and wires don't move on their own.

When you said "Recently had boiler fixed, new fan, in our new house. Tonight I noticed it was very hot even with thermostat down low, checked and the boiler was still on" it gave me the impression that the problem had only just occurred, hence my conclusion of someone 'tinkering' with the wiring but in reality it would have been there from the original installation. Can't believe that whoever commissioned the system failed to notice it.

Yeah really not much luck, only just bought the house and had a failed flue fan, failed timer/programmer and then the uncut wire! At least it is all sorted now.