Pressure slowly rising in combi boiler

[happypeter]

Hi,
I noticed a few weeks ago the pressure in our combi boiler had risen to over 2 bar. I removed about a pint of water from a radiator bleed valve and got it down to just over 1 bar.

Now 3 weeks later the pressure has risen again to over 2 bar. The heating is switched off and has been all summer. The boiler has only been used for hot water.

Its a 3 year old worcester boiler, the small plastic valve that adds water to the system is closed tight

What to do?
thank you

 

[terryplumb]

Has it suddenly increased after 3 weeks ,no change in between ? That would be quite odd.
Do you have a warranty ,if not you need to engage an engineer.

 

[happypeter]

Thanks for the reply, it has been a slow gradual increase over 3 weeks.

It came with a 7 years warranty....just want to make sure its not something non boiler related before making a claim

 

[terryplumb]

Sounds like the filling valve isn't fully closing.

 

[CBW]

You could try and isolate the cold going into the boiler to rule out a potential plate heat exchanger failure. This means you would have no hot water. Failing this, if you’re on a water meter you could do it with meter readings.

 

[happypeter]

isolate the cold going into the boiler to rule out a potential plate heat exchanger failure

There is an isolation valve just before the boiler so it is something I could do. So if the pressure stops rising once isolated its either faulty filling valve or heat exchanger? would that be right?

 

[terryplumb]

There is an isolation valve just before the boiler so it is something I could do. So if the pressure stops rising once isolated its either faulty filling valve or heat exchanger? would that be right?

If you have complied with the warranty stipulations ,then both scenarios would be covered by the warranty .

 

[CBW]

There is an isolation valve just before the boiler so it is something I could do. So if the pressure stops rising once isolated its either faulty filling valve or heat exchanger? would that be right?

Yes that would be right and yes something you could do.

 

[ianmcd]

Its a 3 year old worcester boiler,

Then it is still under warranty so call them out

 

[Madrab]

Serviced yearly?

 

[happypeter]

Yes serviced every year so warranty should be valid

 

[cross thread]

Any old filling loops still connected ?

 

[Matt887]

I've had the pressure rise before due to the system creating hydrogen gas. Had to hot flush with a cleaner to stop the problem

 

[happypeter]

I've had the pressure rise before due to the system creating hydrogen gas

Interesting, any idea what caused the hydrogen? was it from the boiler or somewhere else on the system?
ta

 

[happypeter]

Any old filling loops still connected ?

No it was a whole new system 3-4 years ago, pipes, rads the lot.