Required valve setup

[TonyS65]

You will still have mains pressure against one valve or the other, check valve or not. Ordinary 2-port valves will let by under those conditions.

As Shaun said, you'll have to use high flow solenoid valves as they are rated for mains pressure.

Thanks for the clear up on that matter and that’s why I’ve come on here, I’m good with the idea in my head but as far as the technical abilities of the valves are concerned I’m a bit naive which would end up costing me.
Thanks.

 

[Scott_D]

What about a simple bypass with lever valves. Similar to what you fit with a water softener

 

[TonyS65]

What about a simple bypass with lever valves. Similar to what you fit with a water softener

I’m open to any suggestion, do you mean like a ball isolation valve? One on each supply ; turn one off then the other on ?

 

[Scott_D]

https://www.thewatersoftenercentre.com/images/bypassed2.jpg

You could send the ‘warm’ to be heated by the combi provided it’s compatible.

 

[ShaunCorbs]

What about a simple bypass with lever valves. Similar to what you fit with a water softener

problem is you have an unregulated supply eg no prv so you would need to install a prv on the main and set it up to the correct spec

 

[TonyS65]

problem is you have an unregulated supply eg no prv so you would need to install a prv on the main and set it up to the correct spec

If I remember back a year or two ago I’m sure there is an incoming PRV as we have an average of 110-120 psi which would probably have caused problems unregulated?

 

[Brambles]

Tony,

To do that ie. feed a shower from either an unvented or combi supply you should use a three port L Port solenoid valve that is WRAS approved.

The valve is mounted as close as possible to the shower hot input - with the twin feeds (unvented and combi) feeding directly into the L Port valve.

Control of the valve is through a solenoid - which would normally be 12V or 24V for use in a bathroom / wet room environment.

Don’t be tempted to use a 3 Port T valve - they will not give an effective seal between the ports - they are intended for single entry, twin exit ports, where minor leakage across the outputs is not an issue.

A three port L valve will not start to open the second entry port until the first entry port is fully closed.

I think that Regulations would also require you to fit an RPZ valve on the unvented feed to the three port L valve. Others more familiar with the regulations could probably give better advice on that aspect.

Suitable three port L valves in 3/4 bore are available from Albion - circa £150.

It is not a difficult concept to configure, but obviously you have to instal a second run of 22mm DHW up to the shower installation.

Personally, I would make the switching point at the first point of DHW exit from the UV cylinder, where you could use a 240v actuator - albeit the cost of the valve is the same.

One final point - ensure that you configuration ( if not mounted adjacent to the shower) has no potential to back feed any balanced cold supply.

Good luck with your project

 

[TonyS65]

Tony,

To do that ie. feed a shower from either an unvented or combi supply you should use a three port L Port solenoid valve that is WRAS approved.

The valve is mounted as close as possible to the shower hot input - with the twin feeds (unvented and combi) feeding directly into the L Port valve.

Control of the valve is through a solenoid - which would normally be 12V or 24V fir use in a bathroom / wet room environment.

Don’t be tempted to use a 3 Port T valve - they will not give an effective seal between the ports - they are intended for single entry, twin exit ports, where minor leakage across the outputs is not an issue.

A three port L valve will not open the second entry port until the first entry port is fully closed.

I think that Regulations would also require you to fit an RPZ valve on the unvented feed to the three port L valve. Others more familiar with the regulations could probably give better advice on that aspect.

Suitable three port L valves in 3/4 bore are available from Albion - circa £150.

Good luck with your project

Thanks for your in depth advice, I’ll search for the parts and get advice regarding the regs beforehand

 

[Stigster]

Thanks for your in depth advice, I’ll search for the parts and get advice regarding the regs beforehand

Brambles is "The Man" when it comes to informative and detailed explanations and answers. It is quite apparent over multiple posts that he knows what he's on about. Much respect.

Sorry to go slightly off topic, I just thought that needed saying right now for some reason.