Expansion vessals

[boris.b.barnstable]

Hi,

Just bought a Triton mixer shower to go in the bathroom and note in the instructions that the cold water system "must" have an 'expansion vessal' fitted. Excuse my ignorance, but is this really necessary?? I have a WocesterBosch 35CDi combi-condensing boiler that I understand may have an expansion vessal inside, but I'm not sure. More to the point, I don't see expansion vessals in the Screwfix catalogue or local DIY stores, so if needed where would I get one?

Appreciate your help, as at the moment I can get to the plumbing, but the plasterer is due week after next

Cheers, Boris

 

[megawatt]

Ignore it you don't need one.

 

[boris.b.barnstable]

Thats the exact answer I like!
Many thanks, Boris

 

[Balenza]

If the MI,s state you need one, then you NEED one. Unless the boiler has one fitted.
A float operated valve on a WC can do the same job but its no use if an nrv is located incorrectly thus locking the expanding water in the pipe.

 

[simond]

Yes, Boris, you do need one or you will invalidate your shower warranty.

You can purchase a small one from BES, I think they call it a shock arrestor, or something similar.

Whilst the expansion of HW in a combi system rather depends on the other appliances and lengths of pipework, it will damage components in certain situations.

Worcester now ask the installer to fit external expansion where there is a water meter on the incomer to a combi, because they have an NRV inside.....preventing expansion relief.

 

[megawatt]

SimonD Wrote:

Whilst the expansion of HW in a combi system rather depends on the other appliances and lengths of pipework, it will damage components in certain situations.

What on Earth are you banging on about? The MI's are specifying a shock arrestor on the cold supply?

Yes, Boris, you do need one or you will invalidate your shower warranty.

And, in reality, that means what exactly?

Boris: You really do not need a shock arrestor for this unit/combi combination irrespective of what the installation instructions say in my experience. I have never fitted one nor have I ever come across an installation of one by anyone else and have not had any issues with Triton HP mixer showers as a result.

If it worries you though fit a small shock arrestor (www.bes.co.uk and search for part number 11355) as close as possible to the shower installation and somewhere reasonably accessible. Easy to do and may give you peace of mind for £12 or so

Your call

 

[Nixt]

MI's usualy ask for this only of there are non-return devices preventing hot expansion down the cold feed. They might not be necessary but the last time I had a faulty shower under warranty (Mira) this was the first thing the manufacturers checked for when I called for advice.