varem expansion vessel replacement

3 Jan 2010
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West Glamorgan
United Kingdom
I would like to replace my 18litre varem expansion vessel. My current one has a pre set pressure of 0.7bar and the equivalent one that I can find has a pre-set pressure of 1 bar - would this be suitable??
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be aware that there are different types of expansion vessel.

some are for potable water (i.e. stuff that comes out of taps) and others are for non-potable (central heating systems).
thanks for the information. I have looked on the net and have found one from a company called advanced water company ltd. The dimensions are the same as mine (18 litre, max pressure 4 bar, 190 H x 385 D , 3/4" Connection) although it is red in colour and mine is white. The cost is £56 inc postage so hope this fixes the problem that I have to keep topping up the boiler as it keeps losing pressure and then the pressure rises to approx 3bar and then the pressure relief valve kicks in. Also I pressed the bicycle type valve in on the vessel and I was expecting air to come out but instead it was dirty water!
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your white one is most likely to be for potable water - the red one is for non-potable water.

what is it being fitted to? is it an unvented hot water cylinder?

had a look at the advanced water co website and they seem to do both potable and non-potable
I am assuming it is non drinking water, the reason being is that dirty water came out of the expansion vessel when I pressed the bicycle type valve. Therefore it must only be connected to the central heating system and not the hot water system.
can you post up a pic of the vessel and where it is connected? it may well be on the central heating circuit in which case, no problems.

but if you have an unvented cylinder it may be on the hot water (secondary) side and thus will need to be a potable vessel.
splendid! all makes sense now. that looks like a powermax boiler unit. if so, the expansion vessel is on the heating side so you can use a non-potable vessel. the vessel does not have to be the flat type. you could go to someone like BES ( or even screwfix and get one of their regular shaped vessels - they are about 20 quid for an 18 litre. you will need to get a fixing bracket to secure it to the wall. thanks for posting up a picture!
finally received the replacement expansion vessel - been waiting 3 weeks! Fitted the part on saturday morning and now my boiler works like a dream!! :LOL: :LOL:

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