installing CH expansion vessel

11 May 2006
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United Kingdom
Hi all,

I would like some advise on installing an external CH expansion vessel.

Some background to begin. I have a Vokera combination boiler and it is loosing system pressure when the heating is on, as the pressure gauge reaches 3 bar and the pressure safety valve opens. I have checked the expansion vessel behind the boiler and water comes out of the valve on top of the expansion vessel. To me this indicates that the internal "balloon" has ruptured.

I understand that the simplest and cheapest method would be to install an external expansion vessel on the return pipe as close as possible to the boiler . I can install one next to the mains water filling loop. Is it a good idea to replace the filling loop with a loop that has a t-piece connection so as to allow the expansion vessel pipework be connected to the system? or would it be best to cut into the return pipe and put in a compression fitting t-piece? As the boiler has a safety valve do I need one on the external expansion vessel as well?
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it is best to fit it to the return is fairly straight forward if you have any plumbing experience.
I am planning to replace the filling loop and put one of these in so I can connect the expansion vessel below boiler.;jsessionid=KS2JBA4UKF2SICSTHZOCFFA

This will save me cutting any of the CH pipework. The boiler has a pressure safety valve that I will re-set. If it does not seal properly then I'll have to replace the pressure safety valve. Has anyone done the filling loop tee connection to an expansion vessel before? Is it a good way of doing a EV fit?
not fully sure what you mean...

r u going to connect the ev to the filling loop, somehow.... ?

best desc what yu intend to do better for a better opinion....either way i've never done it this way (or looked to)

first thing that comes to mind is it has a non return valve

as previously mentioned..should go on return, near boiler and of the right size for your water content, and with no valves that could be turned off by some turnip
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Just a quicky,
Have u tried to to repressurise the exspansion vessel first with a foot pump to see if it holds i,ve had a few like this and it works.
nigel, he said water come out the end when he takes the cap off !!
I just thought before going down the the route of a new xspan vessel change shraeder valve repressurise to see if it works, 10 mins work at min cost just to check thats all.
the valve is shooting water out when I press so def gone. As its a sealed system I was thinking of replacing my filling loop with one that has a tee piece as shown in my previous link. The non return valve will connect to the mains water pipe. The tee piece would then allow me to take a pipe from my new expansion tank and connect to the system. This will save me the hassle of cutting in to the 22mm return pipe. What do you think?
the existing filling loop is connected below the boiler. It connects a 15mm mains water branch to a 22mm tee-piece on the CH return pipe. I simply want to replace this filling loop with one that has a tee-piece so that I can take a branch off to connect to a expansion vessel. There will be no valve that could isolate the EV by accident and the job would be a lot easier. Why do you think that I need to put in another tee-piece on the the 22mm return just to have the EV connected?
think some people are confused what you mean, but yeh that would be fine
Yes that's it. thanks for posting the image. so this wouldn't be a problem. Ok thanks for your help
Eternal vessels look untidy. I would (unless not possible) always replace the faulty vessel like for like.

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