Expansion vessel on unvented system is hissing

[CNelson]

I have an unvented system in my home. The fitters that installed it recently came back to replace the expansion vessel as it kept hissing. They said it was a fault with the seal on the expansion vessel. Unfortunately, the new expansion vessel is still hissing.


It sound like boiled water hitting a cold surface, with some gurgling sounds. But predominantly hissing.


When I put the heating thermostat up high for any length of time then switch it off, that's when the hissing happens.


The tundish is dry.


However, the pipe from the expansion vessel to the tundish feels hot.


Can anyone advise about this problem?


Thanks very much.


-CP

 

[Dotty]

I assume you checked they were g3/unvented qualified?

There's nothing you can do on this.

Check that they do have g3 and get them back. If they don't then demand someone who is as they are placing your lives in jeopardy.

 

[albatross]

Take a photo. It sounds rather odd.

 

[Ermintrude]

A photo with annotated hiss please

 

[kay-jay]

What colour is the offending vessel?

 

[TBServices]

What colour is the offending vessel?

Red would be my guess

 

[kay-jay]

Red would be my guess

Aah yes the cider red wine and ale has conspired against me fully reading the op......

 

[happyflyer]

I doubt the hissings coming from the expansion vessel, there's nowt in there to make it hiss, bet there's an AAV next to it that's hissing, where are the photos, need them, you see you got me guessing now, red, blue,white....snake coloured..send the photos.


https://www.google.co.uk/search?q=p...ecnic%2Faltecnic-expansion-vessels%2F;495;296

 

[CNelson]

Here's a picture. The expansion vessel is a zilmet.

 

[happyflyer]

I don't think you could distinguish anyone particular noise in that area, there are so many elbows and the pump is so near there will be lots of noise that sounds like a snake, the whole plumbing job is a complete mess, pump impossible to get at , electrics hanging lose on a board, wish you hadn't sent the photo now, there is just one item there that makes me shudder, two 15 mm couplings(sockets) within 6" of each other, what has the world come to!!! Its been throw in, the plumber needs to go to Specsavers, sorry I can't help it, it's a very low standard. I can't see any pressure gauge for charging???