expansion vessel?

[Mpb-10]

ive fitted quite a few boilers now but would like to get a bit of experience with fault finding, ive a customer with a boiler that when you get it to 1bar, it heats up and works, but then goes up to over 3bar, blows off, and when cools drops to about half a bar, is this going to be the expansion vessel? or could it be something else? cheers for any advice guys.

 

[snowhead]

Yes, classic symptoms of expansion vessel gone.

 

[Mike Jackson]

Expansion vessel lost it's charge pressure.You may get away with re pressurising but it's likely to need replacing.

 

[GrahamM]

Or......maybe the E/V is ok and the link hose/pipe to it is chocked with gunk.
In most cases though, as mentioned, the E/V lost its charge.
What boiler is it?

 

[Rickster123]

But before you do anything check that the filling loop isn't passing!

 

[hommer777]

no nead to strip down the boiler to fit an expansion vessel just fit an external vessel in a conveniant place along the heating pipework

 

[ManchesterGas]

You will also notice that when filling from 0.5 to 1-1.5 bar will happen really quickly, it will be a second or so filling rather than a lot longer

 

[Mpb-10]

Thanks guys so much for all your advice, much appreciated.

 

[Howsie]

Sounds like it needs an additional expansion vessel. How many rads?