baxi 105e rising pressure

[seanmfc]

hi to all that can help on this problem

i have the above boiler and the pvr keeps rising every now and then the dial reads (when cold) to 2-2.5 bar when releasing and putting it back to normal the next day the dial reads empty when looking outside there seems to be a very slow trickle of water from the overflow
my wifes dad was a plumber but in the 70s so he is old skool and not very clued up on combi boilers and in the past we have changed most parts apart from the ev i have done 2 air tests with a tyre guage and the left one as you face it red 0.75 the right one 0.65 and both seemed to be wet

any ideas please

thanks

 

[Rodreguez]

when you say overflow do you mean condensate drain or PRV? also if pressure rises when cold there's got to be something filling the system. if pressure rises a lot wen hot then it could be the expansion vessel is faulty

 

[seanmfc]

thanks for the quick reply the prv drain i mean and nothing is filling the system the filling loop is fine

thanks

 

[Toddyplumb]

Expansion vessel has lost its charge or its diaphragm has split/perished

 

[aggis]

If water trickling out of pr pipe, you need a new prv
Drain down thro' old prv
Pump ex vessel to @ 10-14 psi leaving prv open [ water may come out of pipe]
When at right pressure, fit new prv & fill system to 1.25 bar.

 

[ferret]

if the pressure is rising when cold it must be filling somehow! , if you do chek the expansion vessel it should be pumped to the same pressure as cold fill ie 1bar cold fill pressure 1bar air pressure in vessel.

 

[Rodreguez]

yea defo if filling when cold something has to be filling it. if expansion vessel gone would over pressure with expansion so only wen hot

 

[diesel_ltd]

pressurise your system to between 1-1.5 bar, disconnect and cap your fill loop simples! then you can rule out your fill loop passing ps sometimes you can flick the PRV head a few times to clear a bit of dirt if its still passing and your expansion vessel is holding charge get a new PRV only a few quid

 

[seanmfc]

pressurise your system to between 1-1.5 bar, disconnect and cap your fill loop simples! then you can rule out your fill loop passing ps sometimes you can flick the PRV head a few times to clear a bit of dirt if its still passing and your expansion vessel is holding charge get a new PRV only a few quid

hi

i tried this and no water is passing done the prv and no joy either got to try the ev next

 

[seanmfc]

right just fired the ch up in anger everything topped up & no air in the system after about 10 mins the pressure dropped down to 0 and the bathroom rad was gurgling
any other ideas

thanks

 

[Rodreguez]

try again if keeps dropping u got a leak!

 

[seanmfc]

hi

i cant find any leaks no sign of water anywhere but it is still trickling out of the prv overflow very slowly
when i had the ch on today for 15mins the dial went no further than 2 and after cooling went down to nearly 0

thanks

 

[diesel_ltd]

then you are loosing pressure from prv, the pressure will always rise as your system get warmer you only get a true reading of system pressure when the system is cold

 

[Toddyplumb]

Top it up . Turn on Htg . Sit in front of it . Watch pressure . Do not go anywhere for 10 mins and report back .

 

[tackleburger]

He said in the original post the EV valve was wet. Sounds like new vessel and PRV.

 

[ferret]

hi

i cant find any leaks no sign of water anywhere but it is still trickling out of the prv overflow very slowly
when i had the ch on today for 15mins the dial went no further than 2 and after cooling went down to nearly 0

thanks

ok your expansion vessel has gone , new one needed or easier to install a remote vessel , 8ltr usually does it and fit a new prv .

 

[seanmfc]

just as her dad suspected thanks to everyone for their help

sean

 

[seanmfc]

last question anyone recommend an 8ltr ev or will anyone do

thanks

 

[Toddyplumb]

The original exp vessel is good for systems up to 125 litres. We use BES for exp vessels make sure your system volume is OK while you have the chance

 

[seanmfc]

hi

can anyone tell me whats involved in fitting an external ev and is the old one disconnected

thanks

 

[Toddyplumb]

Just leave old one unless you can easily get to the fitting to blank it . New one T into return pipework

 

[seanmfc]

thanks for your help

 

[diesel_ltd]

i would put a 12L ev in, theres only about a fiver between an 8 and a 12L ev golden rule go over killer if not too expensive

 

[seanmfc]

hi

me and the father in law are going to do the ev monday have taken the advice on here and will get the 12l one made by comap at screwfix could someone comment if this is a correct choice

thanks

 

[Gray0689]

Expansion vessel has lost its charge or its diaphragm has split/perished

Yes if you say it's wet then diaphragm is gone

 

[seanmfc]

bought an ev today with kit am i right in thinking that the fitting is for a cold feed to pressurise the ev and the other end goes into the return pipe via a t piece and the prv outlet goes outside as usual
do i blank the old ev off as well

thanks

 

[diesel_ltd]

post a pic so we can advise you correctly

 

[Toddyplumb]

All you need is expansion vessel and T into return , sounds like you have a sealed system kit . All the othe stuff is already in your boiler

 

[seanmfc]

hi all

have now fitted the ev and everything is now working as it should thanks to everyone that contributed to this thread

 

[diesel_ltd]

thanks for completing the thread but letting us know the end result, ps baxi 105e we'll be talking to you soon again haha (joke)

 

[diesel_ltd]

spelling correction BUT=by