I'm looking to replace a failed "Damixa" tap after only a few years (it drips badly, the vertical swivel is now loose so droops into sink and rubber grips are disintigrating).
Looking at taps I see "high pressure" mentioned. Our water is mains pressure for cold and mains via an instant multi point heater feed for the hot. Never had any problems with that so far, need I take anything into account in choosing a mixer tap? I see many now have a thermostat built in. More to go wrong?
I asked a question here re mixer taps a few months ago. I, too, have high pressure cold throughout the house. My hot is gravity fed. The local plumbing/bathroom shop would NOT install me a mixer tap! They said regulations prevented them from so doing, because the high pressure cold can push back into the hot feed, which apparently is 'verboten' (elfnsafety). I'd have to fit a pressure reducing valve; or run a separate pipe for the hot. Or some such bollocks. I forgot about it. I just managed my recovery from heart surgery with all-over washes at the sink instead, until I was allowed to step into the bath after six weeks.
MM
Shouldn't be a problem. Virtually every mixer tap will work ok with mains pressure on both sides. You only normally get problems when you've got mains cold and gravity hot. At best, they don't work very well and at worst, they force cold water back into the header tank without any hot water coming out.
You can get mixer taps where the mixing doesn't occur within the body of the tap and then travel in a single pipe to the spout, but rather stays as separate hot and cold feeds through concentric pipes, so it doesn't mix until it's left the spout.
Quite - I think this is the common way for those designed for kitchens.
My hot is gravity fed. The
because pushing cold back into the hot feed can overfill the header tank which then overflows into the loft.
Robert
As would a sticking ball valve if no overflow.
Yes, that's the only sort that will work with uneven pressures. Even so, it's difficult to get a decent blend of warm water. It's easier to run the hot and cold one at a time, and let them mix in the bowl or basin. Not very good if you're trying to wash your hands in running water.
I'm not even sure that those taps are available anymore. Haven't seen one in ages.
Tim
The tap spec should show the bar rating. I think 0.3 bar was suitable for gravity fed systems. If you get too high a rating the fllow will be slow. Was with me !
Rob
That's how my tap is fed. Never had a problem. It used to be the norm with cold water storage tanks.
Ah, now that's a new slant. I shall have to investigate. I wonder why the plumbing/bathroom shop didn't offer this as an alternative? Probably wanted extra to run a separate pipe.
MM
I bought a Franke one about 6 years ago, from a quick look at their website, it might be the Olympus model ...
The tap is fed by two 10mm (maybe 8mm?) screw-in copper tails, like many mixers, the concentric bit is all internal to the tap, nothing special to install.
There's no extra plumbing. The mixing is still done inside the tap - but only at the point of discharge, not further back.
As far as I know Franke still make their Davos tap which works in the same way. We've got two, the more recent of which was bought 4 years ago.
And then you find that the shower head is completely blocked up with limescale as I just have after my Ankle injury. Now where the heck does it come from... grrr. Brian
They actually have it the wrong way around - the proscribed activity is to allow a mains cold feed to come into contact with a non wholesome supply of water such that is might contaminate the mains. This can easily be fixed by including a double check valve on the cold supply.
The high pressure cold and gravity hot does not work well in a normal mixer, although you could use a PRV on the cold side and get poor flow rates of both hot and cold ;-) The concentric spout mixers however should be fine.
If you push mains cold back into the cylinder then you will in turn push hot water into the header tank. This can be dodgy if the tank is plastic and not will supported.
You can kitchen ones, but bathroom ones seem to have pretty much disappeared. Been shopping for new bathroom stuff lately. When we last did one about 2000, lost of hand basin mixers came in both types. Nowadays they all seem to be designed for balanced pressures. (I'm sure there a few around, but not obviously)
Following Mon, 28 Oct 2013 09:29:18 +0000, Mike.. . . . :
thanks for all the info, I think I see the issues now.
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