Can water flow rate be measured at the supply pipework?

[Mdljk]

Hello Guys

I recently posted a thread about low water pressure at taps in a new kitchen installed by a company using sub-contractors. I have 0.44 bar of hot water pressure and am getting a flow rate of 4.5 Lpm at the new hot monobloc. The Blanco people say that the taps are rated at minimum 0.3 bar and that a 0.3 bar head should deliver 7.9 Lpm. At my 0.44 bar I should be getting 11.6 Lpm, over twice as much.

The Company are saying that 0.3 bar is the lowest pressure tap they use. That doesn’t seem to me to address the issue. Does it? The overhead supply mains water supply goes on a further 3 metres to supply the Utility Room monobloc (combined hot and cold flow-rate of 25 Lpm) and the central heating boiler. Yet the combined hot and cold flow rate in the new kitchen monobloc is 14.5 Lpm. It seems that both hot and cold are throttled back.

A clogged aerator has been identified as a possible problem and 15mm service valves are installed. Would ‘full-bore’ service valves help? Also is it possible to measure the flow rate at the tails of the pipework in both kitchen and utility as Company is saying the Utility monobloc could be a lower minimum bar rating.

Any advice in any of these areas will be gratefully received as the Kitchen Company are beginning to fade away with the final comment of “We don’t do taps of less than 0.3 bar” without offering further investigation.

 

[Ric2013]

The plumbing sub-contractor is a registered gas and unvented cylinder qualified heat engineer and plumber.

May not mean he's Watersafe Approved as I'm fairly sure it's a separate scheme. It's arguably a cartel. I'm not qualified enough to join, but I'm not sure I would anyway and it would not surprise me if lots of good plumbers are not members as I doubt it gets you much in the way of extra work.

The point is that responsibility for compliance with the Water Regulations falls to the homeowner unless the plumber is a member of that scheme in which case the plumber takes responsibility. But this does not mean the unregistered plumber should be doing uncompliant work. Actually all the more reason for the plumber to make the work as compliant as possible!

 

[Mdljk]

What make is the Utility mixer?

It is 25 years old John g so I confess I dont know. However I do know that currently there are only a limited number of 0.2 bar min pressure in monobloc and nit that pretty while I can find 0.1 bar kitchen taps but they have separate capstan heads on one chassis but are not monobloc. So I assume that since the Utility is cartridge type it is probably 0.3 bar as well.

May not mean he's Watersafe Approved as I'm fairly sure it's a separate scheme. It's arguably a cartel. I'm not qualified enough to join, but I'm not sure I would anyway and it would not surprise me if lots of good plumbers are not members as I doubt it gets you much in the way of extra work.

The point is that responsibility for compliance with the Water Regulations falls to the homeowner unless the plumber is a member of that scheme in which case the plumber takes responsibility. But this does not mean the unregistered plumber should be doing uncompliant work. Actually all the more reason for the plumber to make the work as compliant as possible!

I can confirm that no anti-back flow valves

 

[Mdljk]

It is 25 years old John g so I confess I dont know. However I do know that currently there are only a limited number of 0.2 bar min pressure in monobloc and nit that pretty while I can find 0.1 bar kitchen taps but they have separate capstan heads on one chassis but are not monobloc. So I assume that since the Utility is cartridge type it is probably 0.3 bar as well.

I can confirm that no anti-back flow valves

....have been fitted and it is unlikely that there are any inside the Blanco tap. I think all of this is a result of most homes having pressurised mains hot water from combi boilers unlike my system boiler/gravity hw

 

[John.g]

The cartridge type look very restrictive, only a temporary test but removing the diffuser/aerator might improve matters.

 

[Mdljk]

The cartridge type look very restrictive, only a temporary test but removing the diffuser/aerator might improve matters.

Yes John G

Have remove aerator and am now getting 4.5 L/p (previously 4.2 Lpm ) that is a 7-8% improvement. Utility room at 7.5 L/m (and that is aerated!) is 7.5 L/m 78-79% better than kitchen

 

[Mdljk]

Yes John G

Have remove aerator and am now getting 4.5 L/p (previously 4.2 Lpm ) that is a 7-8% improvement. Utility room at 7.5 L/m (and that is aerated!) is 7.5 L/m 78-79% better than kitchen

Of more interest to me now is the unnecessary 90 degree JG end just before the tail. begin to wonder if most plumbers default to combi-boiler with sub- mains pressure hot water and forget sometimes that some of us have system boilers with gravity hot water that requires TLC with installations.

 

[Mdljk]

Of more interest to me now is the unnecessary 90 degree JG end just before the tail. begin to wonder if most plumbers default to combi-boiler with sub- mains pressure hot water and forget sometimes that some of us have system boilers with gravity hot water that requires TLC with installations.

#end = bend

 

[Ric2013]

Not convinced it'll be your problem, assuming all your pipework is 15mm, but always like to know when I'm wrong, so please do let us know how you get on and what the outcome is.

 

[John.g]

My tap is a "Perlator sink tap (p-ix 501 ib" and I get a very substantial increase in hot flow rate from 5.1 LPM to 6.6 LPM (29%) when I remove the very fine aerator/filter, the hot flows through the centre of the spout and the cold around this central core, don't know if you can get a more free flowing "spout" or not but maybe worth looking into because 6.6 LPM at 70C will give ~ 13 LPM at 40C from cold at 10C which should be sufficient for most purposes. The highest flow I see in the attached Franke file is 6 LPM (hot), from a "Moselle".
I think I actually have this moselle tap with the perlator swivel aerator.

Franke Moselle Bi-Flow Spout Chrome Tap

Franke Moselle Bi-Flow Spout Chrome Tap

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