potterton 28i combi boiler

[giz123]

hi not used this site before hoping someone out there can help ,my boiler that has just come out of warranty, don't you just love them ,goes over system pressure after running for about 20 mins and dumps its guts out of the safety valve .It does not stop running but makes loud gurgling noise's ,have tried bleeding system to no avail please help

 

[kevplumb]

check the pre charge in the expansion vessel

 

[giz123]

how do you do that? do you have to take it off the wall? hot water is ok it only happens when heating is used

 

[kevplumb]

expansion vessel = large red lump usually at the back of the boiler

should have a shrader type valve on it (at the top)

drain the boiler and check the pressure should be around 1 bar

if not pump it up with a bike pump

refill

water press should be approx 1.2 cold

 

[giz123]

found valve ,do you have to drain off the system totaly, or just relive system pressure,have just checked after reliving system pressure and at zero!!!!!!!!

 

[kevplumb]

should be approx 1 bar get the pump out

 

[giz123]

pumped up and tried still seams to be getting high pressure on system 3 bar, checked expansion vessel when warmed up and is at 2 bar is this normal?

 

[kevplumb]

yes

 

[giz123]

not whishing to be a pest but why would expansion vessel lose pressure is it a comon fault ?

 

[kevplumb]

yes the membrane inside is slightly porus

 

[giz123]

Thanks for your help it is much appreciated i will see how things go

 

[gazthepottertonengineer]

expansion vessel probably needs replacing as i have had a few of these go they have an integral store inside them hence the instant bit and because of this are a bit on the expensive side if it does want replacing potterton charge £170 just to give you an idea !!

 

[giz123]

that's a bit crappy it's only just over a year old serves me right for buying british, got stung with rover to
++++++++++++++++++++++++++++++++++++++++++++
just a thought ,but if expansion vessel is n/g would hot water and cetral heating mix ?

MOD

please use the edit key

 

[gazthepottertonengineer]

that's a bit rubishy it's only just over a year old serves me right for buying british, got stung with rover to
++++++++++++++++++++++++++++++++++++++++++++
just a thought ,but if expansion vessel is n/g would hot water and cetral heating mix ?

MOD

please use the edit key

for starters its an Italian made boiler

no would not mix as only place they could possibly mix is in the plate heat exchanger ?? and if they were mixing pressure would rise constantly and not just when central heating was on