vokera combi presure build up

[psk]

hello new to site hoping someone can give me some advice.
ihave a 2 1/2 year old vokera combi which works fine but over the christmas period when it was on for long periods i noticed water outside from the blow off? pipe .when i looked at the boiler i noticed the pressure guage was in the red so i drained some water out of a radiator to release the pressure and everything was fine .a week later the same thing so agian i drained water and also disconnected the filler loopto make sure there wasnt a problem with that but again the pressure is starting to rise.
any ideas as to why would be greatfully received

 

[twgas]

pressure will rise as system gets hot, but water out of blowoff pipe means a new PRV, ex vessel will need checking first, see FAQs

 

[psk]

many thanks for your reply,any ideas of cost?

 

[NEALDEAN]

is it a compact?
if so you are looking at the expansion vessel or heat exchanger.
start with the vessel first it will be cheeper.

should have around 1 bar in it and as you put the gauge on observe if water comes out of the valve, if so its knacked.

neal

 

[arfurrrr]

i put money on it been the heat exchanger , there is technical update on this for heating engineers .

on the cold inlet into the boiler fit a pressure reducing valve , check valve and then a small expansion vessel .

You need a RGI to do the work.

ask him to ring vokera to confirm my advice before he just changes the heat exchanger

Arf

 

[NEALDEAN]

yes i've heard that is the case.
i would always recommend fitting a PRV to all boiler and do so myself. the pressures in some properties are ludicrous and proves too much for some boilers.

be interested to know if its a compact as they seem to be more prone than others.

 

[bengasman]

take the filling loop off, at least on one side.

 

[psk]

thanks for the replys.
yes it is the compact.
,and less than three years old.next question is is it worth having it repaired or have i bought a lemon and would be better putting the money towards a new boiler.
having said all this it is still working perfectly fine apart from having to remove the water every week

 

[psk]

regarding last post sorry i iappear thick but i realise that draining water is not a long term solution as eventually there will be none left.i'm just using it as a stop gap untill i know the best course of action to take.

 

[twgas]

have you disconned the filling loop as suggested

 

[bengasman]

bet you a pint he hasn't
speckled hen please

 

[psk]

yes filling loop disconected

 

[bengasman]

and the pressure is STILL going up?

 

[psk]

yes

 

[bengasman]

The only way I have ever heard this could happen is through a defective second hex.
To check this you need to measure the pressure under the same conditions.
That means either the whole system fully cold, or the same amount of rads on max temp.
The former is the easiest and most accurate to reproduce.
Bring the pressure when fully cold to EXACTLY 1 bar.
Use the system as usual and check the next days when fully cold, and log the difference