Triton Digital shower - do I need expansion vessel?

[howartp]

Hello.

Having had our old electric shower die for the fourth time in 3 years, and having wanted a mains-fed shower for quite some time, I researched digital mixer showers to avoid replumbing the bathroom (pipework embedded behind tiles). We had a combi installed a couple of years ago.

I now have a high-pressure Triton Satellite shower, not yet installed, but reading the manual it says an expansion vessel MUST be fitted (cold water side) to prevent the shower being damaged, but that this expansion vessel might already be within the boiler.

The boiler is a Worcester Bosch Greenstar 28i Junior.

According to the diagrams, it has an internal EV on the CH, and I can see that we have an EV on the CH return adjacent to the boiler. However I cannot see an EV on the incoming cold water.

The boiler manual says we must have a mini EV (part 7 716 102 105) fitted if we have a non-return valve on the incoming feed. I'm not aware there is a non-return valve on the incomer, unless anyone wants to suggest otherwise. Therefore I don't think we have this mini EV fitted. (Is it normal to have non-return on the incoming feed for a regular home residence in the UK?)

That being the case, if I believe the Triton manual, we need one. In their manual, it is fitted between the incoming feed (stop tap and pressure reducing valve) and where the feed splits off to go to the boiler and shower etc. Does it have to go there, or could it go under the bath which is where the Triton mixer controller will be. I reckon there's more room there, which is why I'm asking.

So the questions are, do I need an EV, and where could/should it go? If we need one, do I have to buy the £60+ Worcester Bosch version, or can I get a £25 one from toolstation?

Thanks for your help.

Peter

 

[howartp]

Bump?

 

[Dan Robinson]

Yes you do, but it doesn't have to be Worcester's.


It does have to be for tap water and not one of the red ones designed for central heating.

Look for a Blue or White shell.

 

[denso13]

I'm not aware there is a non-return valve on the incomer, unless anyone wants to suggest otherwise

You'll have to look and find out. Can't tell from here.

if I believe the Triton manual

Why wouldn't you? Follow the instructions or it could be an expensive mistake. The EV can go anywhere in the system, on the cold mains pipework.

 

[howartp]

Yes you do, but it doesn't have to be Worcester's.


It does have to be for tap water and not one of the red ones designed for central heating.

Look for a Blue or White shell.

Thanks very much Dan for this helpful reply - particularly mentioning tap water - by noting this difference I have researched further and subsequently come across the term potable expansion vessel - the results of which allowed me to understand their purpose.

I'll get one ordered - I know a plumber who will do the work, he just hasn't come across potable EVs before.

Peter