Poor hot flow from onoblock

Aug 18, 2008 12 Replies

Had a call today from a bloke asking if I could help with a problem.



The hot water from the monoblock mixer in the kitchen has a very low flowrate. Couldn't really help, mine is the same & I've never got around to sorting it.



Would it be that most 'shed' taps are designed to be used on a combi boiler, rather than mains cold & gravity hot?


I think that's a large part of the problem. Certainly most cheaper monoblock mixers are designed to be used with combis and you have to pay more for one that got better flow charateristics for gravity fed HW.

Another factor might be the insistence on fitting non-return valves in the HW feed if the H&C mix inside the tap. I don't know how much resitance these non-return valves add but it can't help flow. I rather suspect ours might get the heave-ho once our kitchen is finished. ;-)

Tim

Yes - pretty well all of these fancy kitchen taps come from abroad where high pressure water is the norm. The easy answer is to add a pump - that's what I did.

Can you say where one can be bought?

My thoughts exactly.

First I've heard of that? Any details?

I'm going to try my local independant plumbers shop...

If the H&C mix inside the tap, there is the potential for cold water being forced back up the HW supply if the nozzle gets blocked/obstructed.

Consequently, as I understand it, unless the H & C water channels are completely separate right up to the nozzle, then a non-return valve must be fitted to the HW supply to the tap to comply with regulations.

Tim

Don't buy one if they can't tell you what the manufacturers minimum supply pressure is. That alone will get rid of all the unbranded poor quality units from F*ok Yu & their ilk.

Then you need to go for one that is happy with 0.5 bar supply pressure or less. Peglar is a quality make which will I know for sure has some models which will be suitable.

T'other way round, surely? The worry is that water from bug-infested HW systems (perhaps all those people with luke-warm supplies to prevent scalding? :-) ) will be drawn into the mains supply to which the kitchen tap is attached, and thereby contaminate water for other people. Seems a little far-fetched to me, but there you go.

Pete

Well yeah but the regs (as told to me by my plumber) only require the fitting of a non-return valve to the hot supply.

Tim

I wonder if anybody has experimented to see how much difference the removal [or doctoring ;-) ] of the valve makes, on a marginal installation.

Chris

I will as soon as all our plumbing's finished. ;-)

Tim

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