Non return valves

[dave]

Hi

Have just been relocating my water feed tank to an en suite, and temporarily connected the cold water mains supply to a mixer tap on a wash basin previously fed by the above tank. Its made me realise that it would be nice to have clean mains drinking water to the basin, the water out of the tank tastes Sh&(^te. The problem of course is the mixer needs equal pressure feeds of hot and cold to work correctly without back feeding one or the other. My question:- Is there an easy way of connecting a mains fed cold and a tank fed hot, to a mixer without the cold back feeding up the hot tap if both are turned on?? I don't want to change the tap. Would a standard non return valve in the hot feed do the job as used on central heating systems to stop thermo siphoning?

Dave

[cj]

Open block mixer taps were discontinued years ago and are no longer allowed under current regs. All mixer taps now (with the exception of certain shower taps) don't actually mix the water but deliver it via 2 seperate routes to the outlet where they mix as they leave the tap. Also some more expensive taps have non-return valves fitted.

The most likely reason for you being tank fed was either a Bidet or shower is fitted in the bathroom.

Failing everything a std 1/2" non-return valve from your local diy shop will do the trick.

HTH CJ

[Andrew Gabriel]

A standard non return valve in a low pressure feed from a loft tank will let through a dribble, if you're lucky.

[dave]

Thanks for the replies. The basin and suite were put in by myself years ago, also the feed tank. The taps are a 3 hole job and mix before the outlet block. I don't want to change these as they match to everything else in the suite. If as you say Andrew, standard non return valves only give a low flow on tank fed systems ( the head is only about 2.4 Metres), do you know of anything I can use??

Dave

[Palindrome]

A water pump with a pressure tank and switch? That will raise your tank supply pressure to the mains pressure or more.

[dave]

Thanks but I think at that level of complexity I will just use the water to shower in. Unless you can balance the pressures to be equal water will flow either cold up hot or hot up cold. I'm a bit surprised there aren't any simple non return valves on the market. The problem of getting drinking water to a bathroom sink must have been solved in the past, when mixer taps were allowed, without presurising by pump. Regards Dave

[BigWallop]

: > A water pump with a pressure tank and switch? That will raise your tank : > supply pressure to the mains pressure or more. : >

: > -- : > Sue : >

: >

: Thanks but I think at that level of complexity I will just use the water to : shower in. Unless you can balance the pressures to be equal water will flow : either cold up hot or hot up cold. I'm a bit surprised there aren't any : simple non return valves on the market. The problem of getting drinking : water to a bathroom sink must have been solved in the past, when mixer taps : were allowed, without presurising by pump. : Regards : Dave :

Sorry, I'm jumping in at the middle of a conversation, but do I take it the problem is mains versus tank fed supplies?

If, going by what has been said already, you need to balance mains water to the same flow rate as a tank, then use a simple manual gate valve, not a stop c*ck, on the mains feed. This will reduce the flow of water enough to balance it to any flow rate of a tank fed system.

When you get the two supplies balanced then one can not dominate the other so there is no need for any non-return devices. If the mains feed is to supply potable (drinking) water, then a non-return valve can be installed before the manual gate valve. This keeps the non-return valve on the high pressure side of the point where you need to balance your systems and therefore does not interfere with the flow rate.

I'm probably way off with this, but I've said my piece now. :)