Halstead combi pressure increasing and burning cutting out after 2 minutes of running

[adam911]

Hi i have a halstead 102 combi boiler the water pressure increases after few days on its own.

I opened the filling loop to check if the water was leaking while passed the filling valve while its shut and it there was a drip or 2 after every 20 seconds so i replaced this valve and checked again and no water was passing while valve is shut.

The boiler is still somehow increasing in pressure even though i drained it back to 1 bar this morning and now its up to 1.6 bar also the burning is cutting out after its running for 2 minutes with hot water and then water going cold untill i rest the boiler.

Any ideas? i do generally have good knowledge of combi boilers having replaced heat exchange plates and diverter valve in the past but not too sure whats wrong with this? I dont get why the boiler is filling after replacing the fill loop with a new one.

 

[adam911]

Just to add the central heating is working fine. Its just with the dhw.

 

[Aquaheat]

Turn off the cold feed to the boiler that supplies the DHW side. This will prove your DHW heat exchanger. It could be leaking and passing into the system.

Jon.

 

[adam911]

Ok i will try that. But why does the burning go out after 2 minutes of running? Could it be the heat exchange plate as it might be junked up and not taking the heat away from the primary heat exchange and thats why it turns off?

 

[jeff the gasman]

Ok i will try that. But why does the burning go out after 2 minutes of running? Could it be the heat exchange plate as it might be junked up and not taking the heat away from the primary heat exchange and thats why it turns off?

That is exactly why.

 

[adam911]

Why is the pressure going up. Could it also be the little copper pipe that goes to the expansion vessel blocked?

 

[adam911]

Hi ive had a good look at it now.
At first the boiler wasn't recognising when the tap was opened so i took the micro switch of the dhw and and unstuck it and now its working.
The problem now is the when you turn up the temperature for the central heating on the controller it fires up for 30 seconds and cut out for few minutes and repeat its cycle but when it cuts out the central light turns off to say youve switched the heating off but after 2 minutes it lights up again and fires and turns off. It seems like its overheating but the overheat button doesn't pop out so this means its not overheating. Also sometimes all the lights go out and the power flashes and wont kick in untill you turn the controller selector to reset.