Do I need 'high pressure system' kitchen tap?

[northdavid]

Hi

I would start by saying I don't know anything about plumbing.

I moved into a new flat at the weekend and need to get a replacement kitchen tap (to be fitted by a famlily friend plumber later this week).

I see looking at the B&Q website some single hole mixer taps are listed as 'suitable for high pressure systems only'..........how can I tell what I need i.e. normal or hight pressure, what's the differance?

My hot water is supplied from a worcester junior 24i (i think) combi boiler about 2-3m to the left of my kitchen sink at the c. the same level..........

Any pointers would be appreciated

Regards

Dave

[Guy King]

The message from [e-mail] contains these words:

That should be OK provided (as is usual) the combi is fed from the mains water not a tank.

What matters is that the cold supply and the hot supply should be at near enough the same pressure 'cos otherwise the mixer doesn't work properly. This would be the case with a tank-fed hot system being mixed with a mains-fed cold.

[northdavid]

Thanks

The existing mixer tap works fine in terms of pressure split hot/cold and looks great! But leaks (from underneath the sink/tap) when used but not when turned off.......I don't know what make it is or if it's a high or low/normal pressure version.

There are a few taps that look the same, to choose from, some high some normal.......what should I go for?

Thanks

Dave

[Christian McArdle]

99% of combis are supplied by high pressure mains, so a high pressure only tap should be OK.

To test, cover the spout of the existing tap with your thumb. Turn on the hot water just slightly (enough for a dribble, no more) and press as hard as you can with your thumb. If you can't stop the water squirting out sideways, you have high enough pressure.

Christian.

[Tony Hogarty]

This really is a 'rule of thumb' then!

[northdavid]

Thanks

I am almost positve its mains supplied, on the basis I am in a top floor flat, with a (new!) flat roof above, i.e. no room for a storage tank.

How do the high/normal pressure taps actually differ, are the pipe diameters differant?

If I were to buy the wrong tap what would the implication be either way?

David

[Christian McArdle]

Basically, mains pressure only taps have smaller passages. They often mix internally, rather than at the spout, too.

If you had a low pressure system and a high pressure tap, the narrow passages would cause poor flow rate performance. If the high pressure tap also had internal mixing, you will find that turning on both hot and cold simultaneously can lead to cold water at the tap, and the hot water system being back filled from the cold mains with the tank level rising and the overflow running.

If you have a high pressure system and a low pressure tap, it is likely that the system would operate perfectly, probably with a higher flow rate performance than required. You are unlikely to find a low pressure tap that was unable to deal with mains pressure, unless your mains pressure was so high that you really need a pressure reducing valve anyway.

Christian.

[northdavid]

Christian

That's great many thanks.

Is it possible to tell if my existing/faulty tap is high/or low by just looking at it or the flexi tails attached to it?

Would be handy as the existing pressure is perfect.

If not I will just buy low pressure, which seem more widespread and cheaper!

David

[Christian McArdle]

There are some clues. Mains pressure ones are generally more slender. They often have 10mm tails, rather than 22mm tap connectors. They don't usually have twin tube outlets with spout mixing. Low pressure ones are usually twin connection, rather than monobloc.

Christian.