water flow regs?

[Neilglasgow]

Gas safe engineer here but I am struggling on trying to find information regarding what is classed as sufficient for hot water outlets...




New build property have fit the basic ideal logic 30kw which pushes out 12 L per min , this house has 6 different hot water out lets which are
2 bathroom (basin tap , bath tap
1 kitchen ( kitchen tap)
1 clock room (basin tap)
2 Ensuite (thermostatic shower , basin tap)


This has 12 rads and I would say the btu is correct but I am
More concerned about the hot water as if it was my self and the client was wanting a combi I would personally be putting in a 35kw due to the hot water demand but I can't see any regulation regarding what the requirement is for flow rate ect to taps or is there no such thing?




Any help would be great I have contacted wras and they say it sounds a little undersized but this isn't contravention of the Water Reg

 

[ShaunCorbs]

Yes simple way to put it more than one bathroom / shower you require a unvented cylinder

 

[Neilglasgow]

Yes but is there any regs?

 

[steadyon]

Water Regulations Schedule 2, Section 4, paragraphs 8 to 13 inclusive.

Table G8.3 gives flow rates for various appliances (note they are in litres / second, not l/m), but you need to apply "diversity factors" because it is unlikely that all of any one type of appliance will be in use at the same time.

 

[Chalked]

Never mind the regulations.
Two bathroom house deservrves more than a combi.

 

[joni os]

If a diversity calcs. were done on outlets, combi boilers would be less common. In your case 30 Kw, in winter, will do one tap, 10 litres/min and no more. Consider supplementing with unvented cylinder as SC says above.

 

[Neilglasgow]

This is a new build property I am going into and the site manager thinks it's fine to have a basic ideal logic 30kw with a flow rate of 12 litres a min is fine so it's basically up to me to prove them wrong it's shocking what new builds get away with and what people accept

Also Tryed local idea rep but no luck then I phoned ideal technical help looking to see if they would have a guideline if the boiler was capable for X amount of out lets and they don't it's a real grey area I am finding

 

[ShaunCorbs]

simple if they wont put an unvented system it dont do the work

 

[joni os]

!2 litres/min is for 35 degree temp rise. Not good when cold water temp is 5 and you have heat loss between boiler and taps.

 

[Neilglasgow]

Does any one have a link to the exact water regulations for Scotland as al I see is ones for England and Wales I looked up what steadyon said in Google but can't seem to get the exact charts ect for me to prove the plumbing is not fit for purpose

 

[ShaunCorbs]

Does any one have a link to the exact water regulations for Scotland as al I see is ones for England and Wales I looked up what steadyon said in Google but can't seem to get the exact charts ect for me to prove the plumbing is not fit for purpose

theres no written rule

but the system must be fit for purpose

 

[Neilglasgow]

It's crazy we have laws for everything else but something which I think must be a common problem,

A combi boiler Does 2 things and I think manufacturers should actually have a chart for what they would would thibk each boiler could do regarding X amount of outlets :censored:

 

[ShaunCorbs]

It's crazy we have laws for everything else but something which I think must be a common problem,

A combi boiler Does 2 things and I think manufacturers should actually have a chart for what they would would thibk each boiler could do regarding X amount of outlets :censored:

show them this

https://www.worcester-bosch.co.uk/products/boilers/explained

 

[Sparkgap]

Why bring in more unenforceable laws? If you want instant hot water at high flow rates you have to put in some serious boiler power, something like the Andrews Fastflo or Rinnai Infinity, which means bigger gas supply etc. Combis are great for smaller properties but if you've got a family and using more than one or two outlets at once they can't keep up and pressure/temperature will drop.