check valve with tap tails

[Fallout]

Hi why with this tap tails;
http://www.screwfix.com/p/flexible-...-2/91351#product_additional_details_container
Does it say always use a check valve?

 

[Madrab]

Some taps have the mixer chamber within the tap, older taps water mixes from the end of the spout.

This means there could be cross contamination from the hot (cat 2) to the mains cold (cat 1) if not a balanced supply, therefore as per water regs you really really really should have a single check valve on the cold mains to avoid backflow.

 

[Fallout]

Do most mixer taps not need one? Never seen a check valve installed on the cold feed of a mixer tap before.

 

[Madrab]

Again, it really depends on whether it's a balanced supply or not or the tap type/sink dictates its need to be installed. It also protects the potable water supply if there is a pressure drop on the cold side, say when isolated and drained.

It really is a belt and braces approach dictated by the water regs, tho it can reduce flow on the cold side too, so tend not to be installed, maybe why you haven't seen them.

 

[Dextraneous]

It's not whether they need them, it's the water regs that dictates.

 

[Fallout]

On a combi system then balanced flows I guess there not needed then?

 

[Madrab]

It also protects the potable water supply if there is a pressure drop on the cold side, say when isolated and drained.

As mentioned, there are regs and there are other regs, if you wish to keep to the absolute letter of the law then you should install one on the cold side of an 'in the body' mixer tap but if it's just your own house I wouldn't think you be hauled into court if you didn't
If it's in say sheltered housing, flats or other higher risk cold mains shared areas then there are different considerations ergo the reg.

 

[Fallout]

So if you were to fit one in someone's house on a combi would you put a check valve in?

 

[Madrab]

Again, depends on the type of tap. With a monobloc 'in the body' mixer, if on the cold mains of course, then I would certainly suggest it and install it when the mains pressure was adequate.

 

[Fallout]

How do you tell if its an in body mixer

 

[Madrab]

Look in the spout, if there are 2 channels then the water mixes at the end of the spout, these are becoming increasingly rare and are normally reserved to the more expensive specialist taps.

This shows you the theory -

http://www.the-sink-shop.com/images/images_abode/PDF_files/Abode techsingledualflow.pdf

this is a bit out of date as it is now included in the WRAS water regs.