Please help! Boiler ch pump always on!

[LeeD]

Hi

ive recently moved into a new home with a combi boiler witch has underfloor heating downstairs and rads upstairs
The ch pump on the boiler seems to be always on and cannot seem to turn it off even when the programmer is set to off for the upstairs heating and the controls for the ufh are off too!
any ideas would be much appreciated as this is crazing me!
In the programmer terminals there is no cable to the ch off and htw off terminals, should this be?? is it wired wrong?

please help!

Many thanks

 

[telectrix]

does this help?

ST9400A-%2526-ST9400C-Installer-Guide.pdf

 

[LeeD]

Thanks but not really, even when I turn the heating switch on the boiler to off it still has the ch pump light on and still fires up. The stats for ufh are all turned down and there is no heat coming from the floor.

 

[Lenny]

We need a bit more info here before we can offer advice.

Is it a new system in a new house, does it really 'always' run i.e 24/7 or does it just overrun for a couple of hours, what make of boiler do you have??

 

[LeeD]

Grant vortex combi 21e
house 4 years old so yeah newish
not 24/7 but on off on off etc
I'm gna run out of oil at this rate!
And the rads upstairs are always on, I'm gna change the thermostat but that still wouldn't explain why I can't turn heating off at boiler or why?

 

[LankyWill]

You have either have a faulty zone valve Allowing the permanent live down the auxiliary. Or you have a permanent live in the wrong place. You don't need dhw and ch off to be wired.

 

[telectrix]

Thanks but not really, even when I turn the heating switch on the boiler to off it still has the ch pump light on and still fires up. The stats for ufh are all turned down and there is no heat coming from the floor.

so, is the pump just pumping cold water round, and not firing the boiler? if so, then it's not using fuel, is it?

 

[LankyWill]

Make sure the ch cable in the prog goers to the a zone valve brown and not in the greys with others.

 

[LeeD]

No because the burner comes on and the utility room where it is sited is tropical to say the least

 

[LeeD]

Make sure the ch cable in the prog goers to the a zone valve brown and not in the greys with others.

The programmer only has incoming L and N and black in dhw on and brown in htg on

 

[ian.settle1]

When you say a new home do you mean a new home for you or a brand new built home?

If it is the later I would not be playing with it but get the builder on to it as it should be under his warranty period.

 

[LankyWill]

What cables do you have in the programmer. Where do they go? (Joint in airing cupboard most likely). Are you an electrician of any sort?

 

[UNG]

Before changing things you need to get a meter out and do some testing

 

[LankyWill]

Has this problem recently occurred? If yes then I doubt it's a wiring fault and more likely faulty equipment.

 

[UKMeterman]

Some boilers are known for having faulty overrun timers and make the pump run 24/7 !

 

[123]

No because the burner comes on and the utility room where it is sited is tropical to say the least

So the pump and the burner are running?

Looks to me like you have a faulty zone valve as per post #6

 

[ruston]

If it is firing the boiler too , and it is only the utility room that is hot, do you have a hidden frost stat somewhere set wrong?

 

[Leesparkykent]

Do you have a manifold for the under floor heating with a separate pump?

 

[LeeD]

What cables do you have in the programmer. Where do they go? (Joint in airing cupboard most likely). Are you an electrician of any sort?

From the fuse spur it goes into a connector block, from here you have a link for the programmer live, you have the underfloor heating feed and a black labelled 1 to the boiler. In the second connector block there is a grey to the underfloor heating and black labelled 6 to the boiler. In the third connector block black labelled 5 to the boiler and a grey from a 3 core +cpc labelled SBJ. Neutrals all linked in a block too and lastly one twin and earth dead ended in there.

Im an electrician but always worked on streetlighting contracts as a cable jointer so this is not my forte!

There isn't an airing cupboard as it's a combi. Could it possibly be a faulty stat upstairs?

 

[LeeD]

Some boilers are known for having faulty overrun timers and make the pump run 24/7 !

it doesn't run 24/7 just on and off every few minutes or so and I can't even turn the heating off at the switch on the boiler