Red expansion vessel worcester 240 combi

[diamond geezer]

I have found the valve on expansion vessel what do i need to do to put air back in and how will this stop water comeing out of prv
what exactly does the expansion valve do?
how do i fix it?

thanks for the help

 

[kevplumb]

bike or foot pump with the boiler drained

as for what it does

what's it called

 

[ollski]

It is a chamber with a diaphragm inside it, one half is charged with air the other half fills with system water. As the water heats up it expands raising the pressure in the system. Water cannot be compressed but air can so the air side of the expansion vessel compresses to take up the expansion in the hot water. If you have no air in it then the vessel is full of water so it cannot compress, will expand and raise the pressure until the pressure relief valve releases it.

You need whatever you pump up your bicycle tyres with to recharge it, but you need to do it with the heating side drained down.

 

[diamond geezer]

thanks ill try it cant get any worse
this site is better than college learn more

 

[Bahco]

Nice one

 

[diamond geezer]

I have put air in expansion vessel to 1 bar. I have changed pressure relief valve to a new one but every time i put heating on water comes out of prv and once cold boiler shows under 1 bar please help dont no what else to try

 

[kevplumb]

did you drain and isolate the boiler first

 

[diamond geezer]

not sure what you mean by that but if you mean did i turn prv to empty boiler then yes if this is wrong please tell me

 

[kevplumb]

close the service valves on the boiler
drain the boiler
check the pressure
pump it up
dogs wotsits
if not deep doo daa

 

[diamond geezer]

well thats what i basically did apart from shut down service valves...
If that doesn't work what do you think the problem is, its everytime heating comes on it looses pressure and goes to under 1 bar and if i top it up white dial goes other 3 bar comes out of prv and im back to normal

 

[kevplumb]

well thats what i basically did apart from shut down service valves...

please dont do this to me

 

[ollski]

I never close the service valves on any combi.... I'd rather refill and inhibit the system than come back and change a leaking valve. Did any water come out of the pressure valve when you pumped it up?

 

[diamond geezer]

yes it did come out when i put pump on it read 0. so pumped up to 1

 

[ollski]

If any water came out of the bicycle tyre valve on the expansion vessel then its knackered, the diaphragm inside is perished. Only solution to that is replace the entire expansion vessel.

 

[diamond geezer]

How much money will that cost is it a big job
how would of this happened is it just wear and tear

MOD

see item 9