Check / Non Return Valve For Mono Mixer Basin Tap

[DazJWood]

All,

I am a bit confused to the requirements of a check / non return valve for a basin mixer.

I am fitting a Deva Evolution Tall Mono Basin Mixer Chrome - EVO113EX. I have had a search and there seems to be conflicting information on the matter. Some saying you only need one on the cold, others saying on both, some saying not at all.

Could anyone advise whether these are a requirement or not? If it has any impact on the requirement I have a combi boiler for the feed for the hot and normal mains for the cold.

Thanks,

Daz

 

[aqualogic7]

water regs! single check valves on hot and cold are required but if supplies are balanced ie from combi. water supply industry deems that the particular requirement will be met if no check valves are fitted

 

[PlumbBobBob]

i agree. normally if you have tank hot and mains cold for instance then you need one on the hot and cold

 

[AWheating]

it also depends on the tap and its spout. some mix water in the tap and have one spout and need check's some have seperate spouts and dont need checks.

 

[Coleve]

Hi, there is no requirement for check valves on basin fittings in domestic households. Before the present water regs were introduced hot and cold water was allowed to mix in the spout. The new regs outlawed this in that no water was to mix within the fitting. therefore there is no possibility of crossflow. All fitting manufacurers altered their designs to facilitate the new regs. If you happen to buy one with check vavles it is because they are also exported to other countries that require them

 

[WaterTight]

Superb! I so hope that is true. *awaits confirmation/disputation*

 

[spanner]

All,

I am a bit confused to the requirements of a check / non return valve for a basin mixer.

I am fitting a Deva Evolution Tall Mono Basin Mixer Chrome - EVO113EX. I have had a search and there seems to be conflicting information on the matter. Some saying you only need one on the cold, others saying on both, some saying not at all.

Could anyone advise whether these are a requirement or not? If it has any impact on the requirement I have a combi boiler for the feed for the hot and normal mains for the cold.

Thanks,

Daz

All depends on the basin. When filled how far the top of the water line is to the tap outlets. Watford regulations recommend that that if 20mm when basin is full then both with check valves. All is to prevent the back flow and water contamination. If lower then no requirement.

 

[Ric2013]

To answer the OP's question, Coleve is wrong: you can buy and fit taps with in-body mixing quite legally, but you MUST then fit single check valves to both sides IF supply pressures are unbalanced. If you have balanced pressures, as your post suggests you have, there is no legal requirement to fit single check valves, providing the usual air gap requirements are met.

I have had it from this forum though that it may be a good idea to fit check valves anyway as, under certain circumstances, the nominally-balanced hot can end up being higher pressure than the cold...

On a slight tangent, having been told by several people (including at college) that it is not necessary to fit a single check valve on the hot side of an in-body mixer, here is what Dave Norris (water regulations officer from Dyw Cymru (Welsh Water)) has to say on the matter, I thought this was worth sharing. To quote in context, the following was in reply to communication from me acknowledging the need for a check valve on the cold, but could he please confirm the need for a check valve on the hot. He did:

There is a requirement to install a SCV to any shower mixer or tap with unbalanced pressure to help prevent the waste of water due to the risk of the mains cold water(MCW) pressurizing the hot water system and thus resulting in cold water discharging via the vent pipe, cold water distribution to the storage cistern or possibly cause damage to the DHC cylinder unless the mixer has separate waterways to prevent this occurring.

The higher pressure on MCW supply could potentially force the hot backwards through the cylinder under fault conditions and it is then it may be possible in this situation for the AG Air gap in the storage cistern to be compromises with the appropriate protection inadvertently removed and this may also result in the warning/overflow pipe discharging water with the possibility of damage to the property if the cistern is not capable of discharging the water due to the demand. We have in fact previously experienced a similar problem with a customer.