Expansion vessel

So, after calling someone out following my earlier post (boiler wouldn't fire up) and having the Air Pressure Switch and mixed valve replaced, seems the expansion vessel has failed.

When the heating is turned on, the pressure on the tank quickly climbs into the red zone within 10-15 mins.

The expansion vessel read 0 mb and the plumber diagnosed failure because there was a little bit of water near the seal.

The plumber said the expansion vessel needs replacing but I can't see anywhere on the internet this as a spare part or discussion about this part being replaced.

Is this something someone has had done?

You have a "sealed system.
No tank or open vent.
If the expansion vessel has failed then that needs replacing.
Mike
MGC/H2O
Norfolk.

Thanks Mike.

I guess I mean that the pressure dial on he systemate rises.

By your comment I take it the expansion vessel can be replaced, which is what I was wanting confirmation about.

Thanks

Yes it can!
Mike
MGC/H2O
Norfolk

I've now had the expansion vessel replaced (it was quite tricky to get hold of as Gledhill themselves got confused). Made in Italy!

Putting the heating on now doesn't cause the pressure to spike into the red area. Gledhill insisted the pressure gauge itself wasn't made by them so we couldn't get hold of this bit to replace the part that allows water to overflow when the pressure goes too high.

After some trouble getting the air out of the system, the heating will now work (apparently) as it should.

The system now sounds like there is water running around it from time to time. I'm keeping any eye on the overflow. Maybe this is normal and it's so long since I had a proper functioning expansion vessel that I had forgotten about this. Seems that most of my neighbours also aren't aware of the existence of an expansion vessel and its ability to fail.

Hopefully this has sorted it (for now)...

A lot of things which are bought today.
Can be on an open vented system. Or an unvented system.
The choice can sometimes be the installer or what have you.
I would suggest any one reading this post to Google up expansion vessels to learn why they are used.
To be brief;
A sealed system, water expands when heated. Therefore an expansion vessel is required.
There are other ways of dealing with expansion.
If interested look up the Megaflow concept. Rumour is that cost a million pounds to develop.
Also just a hint for anyone interested.
Do not take for granted that what unit etc you have will not go wrong. They all do!
Read the books and learn about your systems before they go wrong.
And find someone who can carry out repairs or supply spare before it does.
Takes a lot of pressure off then!
Mike
MGC/H2O
Norwich
Norfolk.