Aldi kitchen tap and Water Regulations

[spuorgelgoog]

I was looking today at an Aldi kitchen tap in store:

Rather nice, except that closer examination (removal of the aerator nozzle) revealed the spout is a single pipe ie the hot and cold are mixed before leaving the tap.

I thought this wasn't permitted for kitchen taps or taps used for potable water, and this article suggests it may be contrary to the water regulations:

Would it be a breach of the water regs to fit this in a kitchen where (a) hot and cold are both mains pressure, or (b) hot is tank fed and cold is mains pressure? (As my hot water system will be updated in the future)

Owain

[Jonno]

[e-mail] scribbled

If what you're suggesting happened, the water wouldn't mix.

[John Rumm]

The double check valve needs to be in the cold mains feed before the tap. It won't prevent mixing occurring in the tap.

[harry]

It can be fitted if there are non-return valves fitted to both hot and cold incoming pipes. This to prevent hot water getting into the cold system & vice versa. After all we have thermostatic mixing valves.

It might already have NR valves fitted.

[dennis]

You need both on one with a header tank on the hot. If you don't the restriction in the tap can cause the mains water to fill the hot side via the tap and could overflow the header.

[Fredxxx]

Would that be the cold feed side or the outlet?

There should be an airgap between the feed and the overflow so a double check-valve isn't generally needed on the inlet side.

[John Rumm]

Indeed true for gravity fed hot, I was assuming both sides main pressure e.g. combi or unvented cylinder.

[John Rumm]

With a true mixer tap (i.e. not the concentric spout type) then there is the risk of back feeding the cold main with contaminated water - hence the need for the doublecheck on the inlet to the tap. With gravity fed hot, you may also need a non return check valve (does not have to be double) to prevent back feeding the hot water system from the cold main and either overfilling the main cistern, or worse, pushing hot water into it, which could cause it to fail due to softening.

[Chris Holford]

+1 - been there, done that -attached a hose to the mixer tap to fill a paddling pool with warm water; the cold flowed up into the header tank which sprang a leak; brought down part of the ceiling, :(

[NY]

Are header tanks for hot (and maybe even cold) water still being fitted in modern houses? Or have builders finally gone over entirely to hot water cylinder or combi boiler fed from the rising main so as to make sure that hot and cold taps are at the same pressure? Given the choice, I can't imagine any one wanting a header tank - apart from the fact that you have a small reserve supply of (non-drinkable) water for the rare occasions when your rising main has been turned off.

[Dave Plowman (News)]

A decent header tank system with the correct pipework will fill a bath rather quicker than mains pressure water. Even more so if your water pressure is low - as here in central London.

[John Rumm]

That does rather depend on the circumstances...

Here for example, the header tank system took half an hour to fill a bath, the mains pressure system does it in a couple of minutes.

The gravity system was installed with the correct pipework etc, but was totally unsuited to the property (being a house with the upstairs in the roof space). So the cold tank could have at most about 4' of head over the bath.

The incoming mains however is a 32mm MDPE pipe with 5 bar of pressure on it - its like a fire hose and will deliver 30 - 40 lpm without any difficulty...

[Dave Plowman (News)]

That will still work with carefully designed pipework. It's what this house had when I moved in.

[spuorgelgoog]

I shall have to buy check valves and remember to fit them on the *tap* side of the water heater and not the supply side (the heater uses supply side e xpansion instead of an expansion vessel)

The tap itself looks and feels pretty solid and has a 3 year guarantee for a penny under £30.

Owain

[John Rumm]

ISTM that if a DC valve is needed to protect the cold main from contamination, it would be good to protect it in the house as well as in the street - so a DC right before tap sounds good ;-)

Now and then there are some decent ones out there for not much.

[John Rumm]

I can't imagine what size the pipework it would have to be ;-)

(I suppose if you pumped it, it might be ok - but it really was not worth fiddling with for so many reasons)