Baxi 105E Expansion Vessel

24 Jan 2011
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United Kingdom
Hi folks was on here last month whilst I was away from home trying to figure out what was happening with my boiler.

Basically the system pressure was fluctuation between 0-0.5 bar to 2 bar, I've just got back and checked the Schrader valve on the top of the expansion vessel and got air, practically nothing but no water so am I right in saying the vessel looks sound?

I just popped a little air in there with the heating off and brought the pressure upto 0.5 bar cold and fired up the system which brought it upto 2 bar it's dropping off again so I presume the acid test would be to flatten the water side and charge the vessel to 0.5 bar then refill the heating loop and see how it fluctuates?

Thanks in advance
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Could just be residual air in the vessel, raise the c/h system pressure to 1.5 bar then press the schraeder again, see if you get water out of it before the pressure hits zero
no that doesn't mean vessel is ok, it means that the diapragm is not knackered but what pressure air as in there, waht gauge did you use ? you probably need to re charge the vessel, you should have around 0.75 bar - 1.0 bar
Hi I didn't measure the pressure cause there was basically nothing left, quick blast of air when I pressed the needle valve in then nothing, I just put a small amount of air in there to see if I got a pressure increase.

I took the system pressure to 0.5 with the water side full and cold on the boiler gauge, I've had it running upto max temp and the system pressure was at 2 bar I'm just waiting on the system temperature dropping to see what the pressure settles to!

According to the manual it came precharged to 0.5 bar, it's an 8 litre vessel so I know there's nowhere near that amount of air in there. I take it I'm trying to balance the air in the vessel against the water in the loop??

0.5 in air side with too much water in the water side would lead to high pressures??
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you need to drain of htg side on blr. close iso's and drain using doc on lhs below pump. leave doc open whilst pressurising vesseland now fill it to between 0.75 to 1bar. close doc, open iso's refill htg , vent pump and you should be okay.

As muggles says before you do this I always put some extra pressure into system (up to about 2bar) then check schrader for water.
Ok I'll stick some extra into the system tomorrow, it's settled back down to 0.5 bar so it looks pretty good initially.

By Iso's do you mean the supply and return valves for the heating loop. Is the doc a local drain within the boiler??

If I'm not sure I'll just get it limping over for now and get a local plumber in when I get paid!!

Cheers for the help guys much appreciated

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