Help and advice needed recharging EV greenstar 30si

6 Sep 2005
Reaction score
United Kingdom
Hi all.
I went to do my normal bleed and top up routine yesterday- ready for winter,and found my pressure gauge at zero. Anyway,a bit worried....I top up to just over 1bar....and turned on full...all radiators open,ready to bleed. It was then I noticed the pressure raising to 3 bar and over...checked outside prv outlet and indeed it was weeping water. I shut the system down and cooled ( pressure now on about half bar ). Checked expansion vessel schrader valve to see if any water was present - and it was dry, however there was no air in there what so ever. I drained more water from the system to zero....then tried recharging with my bike pump - but there was no way I was getting air in there. Today I purchased a new schrader valve core and replaced...before doing so,gently poking around the schrader hole,which seemed to give a little,with a tiny hiss...and got a bit of crap out . So fitted new schrader core and proceeded to recharge. I’ve got to 1bar...but noticed the water pressure was matching it...also at 1 bar. I’ve bleed a radiator again to get down to zero pressure water side ...and the air pressure in the EV also dropped to zero!....tried once more - bleeding - zero water - repressurize the EV...again both pressures have gone to 1 bar. I’ve stopped now as don’t want to drain anymore water without advice. Please any it normal for both pressures to rise until I get to a point where the bellow inside is more than the water pressure ( ie did I originally over fill with water...which is sitting in the EV
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You need to pressurise the air side of the expansion vessel with the water side open to atmosphere. Open boiler bleed valve, or radiator bleed valve if easier. Attach pump and increase air pressure to value in boiler manual. Note water will come out of bleed points as air pressure increases. Remove pump, close bleed valve(s) and pressurise as normal. If PRV has lifted it may well not re-seat properly and need to be replaced.
Thanks for your reply. I open the radiator bleed valve...and water comes out (as pressure on both air and water = 1bar).....are you saying keep the bleed valve open until no more water is coming out? Do I basically have to drain the system and leave a port open to atmosphere?
AH,I think I get you. I’ve just opened the highest bleed point ( loft tall towel rail ) bleed until nothing came out....recharged EV to just under a bar - the water pressure now just reading about .3 bar ....which I assume is the fall pressure. Fingers crossed this may work. I’ll report back. Thankyou again
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Jobs a gudden I think. Just ran boiler for half hour on full temp....water pressure raised by about 0.25 bar. I’ve kept a bag on the prv outlet outside to monitor any leakage. Thanks again oldbuffer
Just another quickie.....have you used sentinel aerosol inhibitor before? Any good? I wanted to top up the inhibitor ( me being paranoid ) ...maybe I don’t need’s a new build property - 4 years old.
If you mean Sentinel Rapid Dose, I've used it, but I'm not really keen. I find it hard to apply, but that might just be me.

My favourite is a towel rail / radiator with bleed point on top left or top right (vertical facing). Turn off both radiator valves (making a note of number of 1/8 turns on the lock shield). Open bleed valve, remove blanking plug or bleed valve plug, syphon out just over a litre of water, add 1 litre X100, replace plug, close bleed valve, open valves to original position. Run system to circulate, then bleed towel rail / rad. If large system (11+ radiators) use 2 litres and syphon out just over 2 litres.

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