Low pressure basin mixers.

[Etaoin Shrdlu]

We have gravity-fed hot water, and mains-fed cold. Missus wants a new basin in the bathroom with a mixer tap. I'd say we have about .2 bar hot water pressure, and the mains cold water pressure is, obviously, much higher. I can see that there are lots of low pressure mixers out there, but I often see them described as being good for low pressure cold water, too. I need to know if they actually work when the difference in the two is so great. Or will the cold just push the hot back into the header tank?

[spuorgelgoog]

You can try a pressure reducing valve on the cold inlet to the mixer, to bring it down to closer to the hot water pressure.

Owain

[John Rumm]

You need to look for one with a concentric spout, where the mixing happens outside of the tap. A conventional mixer will probably just reverse fill the hot cylinder unless you have a non return on the hot and possibly and pressure reducing valve on the cold.

[Mike Barnes]

We have gravity-fed hot and mains-fed cold, with mixer taps everywhere. The pressures are equalised (more or less) by having a pump on the hot. It works pretty well.

[The Medway Handyman]

Go to a proper plumbing place, not a shed.

Somewhere like

They will sell you something that works.

[Etaoin Shrdlu]

I used a reducing valve on the bath mixer, but it required that the cold water be reduced almost to a trickle. I ended up fitting a pump to the bath hot water, so now it's better than it's ever been, and we can even use a shower using water from the hot tank. A reducer might work better with the basin, though, of course, because of the smaller volumes of water going through it. I have a load of reducers in the loft, so I'll probably end up using one.

[Etaoin Shrdlu]

I'd forgotten about the concentric mixers - I'll definitely be looking for something like that.

[Etaoin Shrdlu]

I did get a pump for the hot water, last year. The easiest way to fit it was to stick it on the outlet from the hot water tank, which pumped all the hot water in the house. But there were a few annoyances, not least of which was the noise. There is also a small basin in the downstairs bog, and when the pump kicked in on the hot tap, you were guaranteed to get a wet crotch :)

I bit the bullet and moved it under the bath, at the same time fitting an extra flow switch on the cold water. I'd say this arrangement is perfect right now, but I may end up having to rearrange things so that the upstairs basin is also covered by it.

Our downstairs gravity-fed hot water is fine - even from the kitchen mixer tap. Although I can tell that's a concentric one.

[Etaoin Shrdlu]

There seem to be loads of tap suppliers on the web (or are they all the same one with different names). I can't tell which are the good ones, so the recommendation is appreciated.

[Dave Plowman (News)]

You may have a problem finding one in a style you want - as they are more to prevent potable water mixing with stored hot, ie in a kitchen.

[Etaoin Shrdlu]

Hm, I'll expect problems then. Thanks for the warning.

[Andy Burns]

Could you re-plumb the bathroom basin cold to be from the same cold tank that feeds the hot tank, or is that verboten? (brushing teeth with eau de dead pigeon etc)

[Etaoin Shrdlu]

My missus actually brushes her teeth with hot water. But she's Italian, and maybe that's what they do over there. I'll have to remember to ask one day.

[Dave Plowman (News)]

At one time, that was fairly standard practice in some parts of the country - only the kitchen cold being direct from the mains.