Vokera compact combi boiler losing pressure

[mikeyw]

Hi,

I realise (through searches) this is a fairly common fault and often the culprit is the expansion vessel but on searching for mine i stumbled across what might be causing the issue. Overnight the boiler often loses pressure so that the heating wont come on in the morning as follows

No pressure left

I took the front off to see if i could see he expanison vessell but no joy

However while checking the side i noticed there is a leak - i assume this must be the cause

So :-

a) Would you agree
b) How would i tighten this if possible ?

I'm hoping the part doesnt need replacing.

Thanks in advance,
Mike.

 

[McCombi]

To the rhs of pump there is a drain point with plastic tube attached, drain boiler completely from here.
Take out the circlip and remove part that leak is at, should just need a new o ring.
Check the expansion vessel with drain point still open and pump up if necessary.
close drain point refill to around 1.2 bar.
Best to isolate electrics first

 

[McCombi]

Oh and you definitely shouldn't be in the combustion chamber part of boiler.
Didnt look at the pics properly.
I would advise getting an rgi in to make sure combustion is ok.

 

[ianmcd]

That is a common fault with the compact, the expansion vessel is behind the boiler and the schraeder valve is at the top of the boiler below the flue

 

[mikeyw]

To the rhs of pump there is a drain point with plastic tube attached, drain boiler completely from here.
Take out the circlip and remove part that leak is at, should just need a new o ring.
Check the expansion vessel with drain point still open and pump up if necessary.
close drain point refill to around 1.2 bar.
Best to isolate electrics first

Thanks - is it pretty straightforward to drain the boiler ?

It's not something i've done before....

 

[mikeyw]

That is a common fault with the compact, the expansion vessel is behind the boiler and the schraeder valve is at the top of the boiler below the flue

Can you see the the valve in pic 3 anywhere ?

I'm not going to ber able to get to the vessel itself but hope i can at least fins the valve and pump it up slightly

 

[ianmcd]

yes its easy follow the drain tube and you will see a brass nut with a nipple on it slacken the brass nut and water will drain into the clear plastic tube just drain all the water into a basin or bowl of some description , when finished tighten the brass nut and top up the pressure via the filling loop, DO NOT use the PRV to drain the boiler

 

[mikeyw]

Thanks - is it straightforward enough to remove that clip ?

Don't want to force it and break it or make it unusable again

 

[mikeyw]

Finally located the bugger of an expansion valve - well hidden top back !

I pressed the valve and nothing no air whatsoever, i've tried adding some back in ( a job in itself !) and was wondering what sort of pressure i should inflate to, also will it stay at this pressure or will it need topping up all the time ?

TIA,
Mike.

 

[ianmcd]

you have to charge the expansion vessel when the boiler is drained and the drain valve is still open as when you pressurise the vessel lots more water will come out of the drain, once the water stops coming out charge the vessel to 0.8 Bar then close the drain and pressurise the boiler, you can not charge the vessel any other way

 

[mikeyw]

Thanks for you help Ian - i'll get the new O ring and post some photos of what i think i'm doing just to be 100%.

Always nervous tinkering with boilers but it sounds like this is do-able for me

 

[mikeyw]

Sadly guys after doing all this work the boiler is still losing pressure, this only happens when it's not in use ie overnight.

Any ideas what the problem could be - the EV is correctly pressured now so that doesn't seem to be the issue.

tia,
Mike.

 

[MeterMonkey]

Sadly guys after doing all this work the boiler is still losing pressure, this only happens when it's not in use ie overnight.

Any ideas what the problem could be - the EV is correctly pressured now so that doesn't seem to be the issue.

tia,
Mike.

Sounds like its time to call in a professional.