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Discuss Can water flow rate be measured at the supply pipework? in the DIY Plumbing Forum area at PlumbersForums.net

Messages
87
Okay. So the mixed flow being less than the cold alone remains a mystery. But basically the mixer tap works and were the issue flow rates alone, I'd suggest the customer ought to be happy. 4.2 l/m hot is borderline for a kitchen tap, but if the customer wants a mixer, that may be about right.

An installation in breach of the Water Regulations (unless the plumbing firm is a Watersafe Approved contractor) leaves the customer liable to (unlikely) prosecution. I would recommend the OP contact the local Water Board ("Water Undertaker") and discuss the matter with the Water Regulations department. If check valves are not fitted, that is probably a breach of the Water Regs (nothing in the Blanco link supplied suggests check valves not required).

But fitting check valves here would probably ruin the flow rate on the hot side so the company that supplied and installed the tap should have initiated a discussion in which the company states the tap installation won't flow properly (once the check valves are fitted) so does the customer want to have a hot water pump fitted/pipework upgrades or would he or she not prefer a more suitable tap instead? I'd have that conversation - which is probably why I'll never be the cheapest.

I would not have wanted to fit that specific tap to a mixed-pressure system and would not expect the customer to know anything about plumbing hence I would not have recommended it. I'd have suggested a biflow tap (no check valves required) and, as for the time to get hot water, how was the old tap and what does the customer want to to ensure the new tap is no worse? At a guess, I'd suggest the firm may have good intentions but possibly lacks a qualified plumber - hence a lack of technical understanding.

For what it's worth, the hot washbasin tap in my own home is a 1/2" hot only tap. I also have a vented cylinder. The bathroom is on the first floor, the cistern on the loft floor above the first floor and the house has low ceilings. I probably have 1.5m head. I can't remember the exact flow, but, from memory, I'd suggest it's nearer 9 than 4.2 litres per minute (possibly it's as much as 12). I have hot water in under 15 seconds. Yes, the pipework was designed and installed to the nth degree, but what really helps is the tap mechanism is to BS1010 and specifically designed for 0.1 Bar use. The continental firms don't really get British systems as the UK refused to accept mains pressure hot water was safe until the foreigners had used it for 50 years, so our older-design mechanisms with washers really do work best with lower pressures.

Try giving PeglerYorkshire a ring and seeing what the flow rates are for their 0.1 Bar kitchen mixers?

The problem with changing the isolators is that there isn't a huge flow rate to begin with, so such a restriction as a 10mm bore valve won't be causing very much restriction: the restriction, it would seem, is the tap itself, but it may help - slightly.
Thanks Ric2013

The plumbing sub-contractor is a registered gas and unvented cylinder qualified heat engineer and plumber. At the same time he's a had several call backs. I agree that full-bore isolatirs is unlikely to help especially as.***,he's gone from plastic to copper on the last metre or so and had to adjust his second fix so that he has a JG elbow giving him a 90 degree short pioe-run to take him to the tap-tail. Even I as a diyer knowcthat is to be avoided especially in gravity systems.

Would re-adjusting the last metre or so (reverse fitting) so that you eliminate that (unnecessary) final bend alieviate the issue?
 
Messages
87
Thanks Ric2013

The plumbing sub-contractor is a registered gas and unvented cylinder qualified heat engineer and plumber. At the same time he's a had several call backs. I agree that full-bore isolatirs is unlikely to help especially as.***,he's gone from plastic to copper on the last metre or so and had to adjust his second fix so that he has a JG elbow giving him a 90 degree short pioe-run to take him to the tap-tail. Even I as a diyer knowcthat is to be avoided especially in gravity systems.

Would re-adjusting the last metre or so (reverse fitting) so that you eliminate that (unnecessary) final bend alieviate the issue?
Sorry Ric2013

I can see now that you've already covered that and you don't think its an issue.

Thanks
 

Ric2013

Plumber
Messages
3,133
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!
 
Messages
87
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
 
Messages
87
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
 
Messages
87
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
 
Messages
87
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.
 
Messages
87
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

Plumber
Messages
3,133
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.
 

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