Have been looking for ages for a kitchen mixer tap.
Almost every one which is otherwise acceptable demands a water pressure of 1.0 bar or higher. We'd struggle. Mains cold is fine, but open system HW with, perhaps, a five metre head would struggle.
We do have mixers on upstairs and downstairs basins - and they are OK. But I think I remember searching out ones which claimed to work at lower pressures.
How bad would it be to use a 1.0 minimum tap?
There is a definite pressure (ha ha) to get one that is white. Already cuts down the available products by over 95%.
Probably unsatisfactory. I fitted a high pressure tap without checking before hand and it gives a pathetic trickle.
Recently bought one of these
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from them, it works fine with 10M head.
Their web site says they sell 105 low pressure kitchen taps, unfortunately, when you filter on white it only gives 3 options and only one of those is actually available in white!
They all work better with equal hot and cold pressures. They all work after a fashion[1] with unequal pressures.
The problems you're likely to get with the hot pressure being too low are these:
Using with just the hot tap open, it may take a long time to fill a bowl for doing the washing up.
Getting a blend of hot and cold water may range from the difficult to the impossible. If the mixing is done right at the output end of the spout, blending is usually *possible* - but you'll need to have the hot tap opened a lot and the the cold tap only just cracked open. If the blending is done further back inside the tap, opening both taps together will result in cold water being forced back up the hot pipe into the hot cylinder, and no hot water reaching the sink.
[1] By which I mean that they will dispense both hot and cold water - though not necessarily at the same time.
Really, mixer taps for kitchen use with low pressure HW, should be of the former design, where the hot and cold supplies go down separate channels in the spout (as normally hte cold water is from the mains in the kitchen). So as to avoid the problem with unbalanced water pressures
Don't the latter type tend to incorporate check valves in order to prevent such back-feed? This in turn causes additional loss of head/q
Indeed. Tbh the whole idea of cold water pushing a say minimum 8ft head of hot water rather than take the easy route out of the spout 8inches away does sound rather fanciful...
I've never found that to be a problem really. Though it does seem to vary on the tap.
I did however make provision when I refitted the bathroom to use the bathroom pump to pump the HW to kitchen sink, in cae I want to do that when the kitchen gets redone
Most high pressure taps specify 1 bar as the minimum. Performance may not be stunning, but it ought to be usable. Note also that 1 bar is all that most water suppliers are required to give you as a minimum pressure.
I don't think the problem is that of hot water backflow so much as a _further_ reduction of hot water flow (unless you're using your thumb over the end of the spout to generate a jet of water to better rinse out a cup).
Our Kitchen mixer tap uses seperate spouts to externally mix the hot and cold flows (mains cold water with 0.7Bar of hot water) to avoid this flow reduction effect.
That proved very handy when the already poor flow rate from the hot eventually got down to a pathetic trickle about 12 months after having the kitchen extension built and fitted out.
I used an old fashioned push on washing machine hose adapter so I could divert the cold flow into the hot flow to back flush the hot water plumbing. I had to keep a tight grip on the adapter to stop it blowing off the spout and cyclically squeeze the uncoupled hose end of the adapter to generate pulses of backflushing pressure.
I think it only took a minute or two to restore the hot flow to better than new and ISTR that I may have 'given it another 5 minutes to be sure'. The 'cure' proved to be a permanent fix to the problem since the hot flow has remained just as good these past thirty years or so.
In fact, immediately afterwards, it seemed as though the hot flow rate was faster than the cold flow rate (possibly a psychological effect akin to the effect of watching a 'Vertigo' labelled vinyl disk being stopped after observing it spinning for a minute or so where it then appears to be moving slowly backwards even though it has actually stopped).
In any case, the flow rate is on a par with the cold tap even now. I'd need to actually measure the flow rates to do a proper comparision but whatever difference exists, it's never been enough to motivate such an experiment.
If I'm reading that right, it sounds like there was some kind of blockage in hot pipe to the tap --- were you not concerned about where that stuff ended up?
I figured it might have been some sort of debris, left behind due to the plumbing work, which had piled up somewhere in the pipework. I figured that any such debris would be loosened and broken up enough to be flushed out of the tap into the sink waste.
I don't recall spotting any such debris landing up in the sink but figured it wouldn't necessarilly be visible due to dilution in the high flow rate stream (when I released pressure off the end of the hose adapter, I'd see the total of both the hot and cold flows of water going into the sink).
Any of the heavier particles being backflushed into the hotwater tank would simply settle to the bottom of the tank where they could remain largely undisturbed by the incoming cold from the header tank.
I didn't think, as was suggested by Andrew May, that I was dealing with an 'air lock' issue since the extended pipework had no air lock loops over the visible portions and no obvious need for any such convuluted routing into the kitchen extension.
Any such hidden 'siphonic' sections would be a good 12 feet or more below the header tank water level were any trapped air should have eventually dissolved out over the 12 months or so that it took to worsen to the point I felt I needed to take some action. If it had been trapped air, the condition should have eventually resolved itself rather than get worse.
I'm pretty sure my backflushing exercise must have exorcised some sort of debris based blockage, either back into the hot water tank or else down the sink waste outlet. Either way, I'd effected a permanent cure with no odd after-effects coming to light over the subsequent 3 decades so it's all rather academic as to exactly what the true nature of the problem was.
The important thing in this case being that it took a mere 5 minutes or so of 'splashing good fun with a washing machine hose adapter end piece and the kitchen mixer tap'. Take heart, lads. Not every DIY plumbing repair calls for hours of work, blowlamp in one hand and a crowbar in the other. :-)
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