Single check valves in bathroom

[Super_Paulie]

Happy Friday peeps, just after a sanity "check" here. 

 

Just mocking up the bathroom plumbing, do I need single check valves on the cistern and the hot and cold to the in-wall sink mixer? I have confined with the company that the mixer doesn't have them built in. 

 

The shower is a DuoTurn iBox2 which I believe has checks built in already.

 

Image attached, hot and cold supplies coming in from the left, I'll have to jump over the hot, just mocked up for now.

 

Edited 3 hours ago by Super_Paulie

[JohnMo]

None of our outlets have check valves.  If your hot water source is an unvented cylinder (or combi boiler) all your water (hot and cold) is wholesome.  So my assumption is an UVC or combi - vented you may need checks valves everywhere you can get mixed hot and cold water

Edited 2 hours ago by JohnMo

[Nickfromwales]

If it's a balanced system (eg UVC with control group @3bar) then no need; that is unless it is written in the manufacturers installation instructions that they do not come with any but you have to install (if necessary).

 

1 hour ago, Super_Paulie said:

I'll have to jump over the hot

https://www.screwfix.com/p/flomasta-copper-solder-ring-equal-full-crossover-15mm/96070?tc=ET2&gclsrc=aw.ds&gad_source=1&gad_campaignid=19822796606&gbraid=0AAAAAD8IdPxHKHuWc7wissg6h-4JWisF7&gclid=CjwKCAjw7p_UBhBlEiwAhpIs7xQeIdwwnDVV-N7hY0fZuKkbvp1uWTlwrjf5adZGFYo8aOuCvNHX6RoCk5oQAvD_BwE

[Super_Paulie]

Just now, Nickfromwales said:

If it's a balanced system (eg UVC with control group @3bar) then no need; that is unless it is written in the manufacturers installation instructions that they do not come with any but you have to install (if necessary).

 

https://www.screwfix.com/p/flomasta-copper-solder-ring-equal-full-crossover-15mm/96070?tc=ET2&gclsrc=aw.ds&gad_source=1&gad_campaignid=19822796606&gbraid=0AAAAAD8IdPxHKHuWc7wissg6h-4JWisF7&gclid=CjwKCAjw7p_UBhBlEiwAhpIs7xQeIdwwnDVV-N7hY0fZuKkbvp1uWTlwrjf5adZGFYo8aOuCvNHX6RoCk5oQAvD_BwE

 

It's a combi John.

 

That's what I'll be using Nick, yep. 👍🏻 

 

So no checks at all, not even on the bog? 

[Mike]

My understanding is the same as @JohnMo's - when mixing hot & cold you need single check valve. Regular cisterns have an air gap between the water inlet valve & the water level, which is fine. Double check valves for outside taps. Washing machines & dishwashers are required to have built-in valves, but nothing to stop you adding another.

[Nickfromwales]

9 minutes ago, Super_Paulie said:

 

It's a combi John.

 

That's what I'll be using Nick, yep. 👍🏻 

 

So no checks at all, not even on the bog? 

If it's a combi you do get pressure drops across hot > cold, but it's still classed as balanced, so all good.

 

"Bog" has an A-B gap so water from the cistern cannot enter backwards into the system.

 

Number of single checks required = 0.  

 

On my combi I put a TMV which does 2 x wash hand basins @46^oC, as the slower run outlets get stupid hot and I can't be arsed flicking the handle of the tap left/right to get the temp spot on. Just flick to the hot, open her up, and the same temp every damn time. Happy days.

[Nickfromwales]

3 minutes ago, Mike said:

My understanding is the same as @JohnMo's - when mixing hot & cold you need single check valve

Only if open pipe 'gravity hot' and then cold mains the other side  

[Super_Paulie]

I wash my face in cold water anyways Nick! 

 

Great, saved me a few quid and more importantly saved the space for my manifold.

 

I did put checks on my kitchen sink mixer, I guess that wasn't worth it but the job is done and I ain't going back to it. Was easy to attach the tap flexis too I guess.

[Mike]

4 minutes ago, Nickfromwales said:

8 minutes ago, Mike said:

My understanding is the same as @JohnMo's - when mixing hot & cold you need single check valve

Only if open pipe 'gravity hot' and then cold mains the other side  

Must be the French rules clouding my memory :)