15mm to 22mm pipe for bath filler

[sparer]

Hi,
I've been looking at the plumbing in my bathroom and in particular the bath filler. I can see that the hot water supply from the boiler is in 15mm but the hot water supply to the bath filler is in 22mm. Is there any point to this? Surely the flow is restricted by the 15mm at the boiler.

Thanks

 

[Dan Robinson]

You have a combi boiler of sorts - they all have 15mm outlets.

22mm to a bath is standard practice dating back to the days of gravity fed domestic water systems.

 

[sparer]

Hi Dan,
If I were replacing the pipework, is there much point in putting in 22mm or does 15mm suffice?

Thanks
Richard

 

[Dan Robinson]

Depends on the plans you have for the boiler.

If you are going for an unvented then 22mm.

If going to a combi then 15mm will probably be fine.


We need figures on the pressure and flow of the water main (before boilers and the like are taken into account) to give too much advise on this front. Your are going to want 20 litres a minutes at 2 or 3 bar to make an unvented worth installing.

Any less and you will be looking at the water main needing upgrading; or an equivalent solution.

 

[sparer]

Yeah. I wish id asked the question a month ago because I just rerouted the mains in 15mm nearly used 22 off the 25mm mdpe pipe but its done now and would be a real hassle to move it. My 18l pm was from the kitchen tap which takes quite a tortuous route so i'm hoping if I test it near the main I might see better. Hopefully the magic 20 litres.

I guess I'll use 22 for the filler since it is convention and it allows potential upgrade possibilities. Does that seem sensible?

 

[Dan Robinson]

Indeed.

 

[sparer]

Thanks again Dan.

 

[newbuildinstaller]

woooahh hold your horses. If you have a baby combi 24-28kws a bath tap piped in 22mm can pull too much water through the boiler resulting in luke warm bath water. A combi can only heat "x" amount of water per second.

Pipe it in 15mm a UV cylinder would still have a bath piped in 15mm and work fine. Unless you plan of going back wards and fitting a tank and cyl stick with the 15mm.

 

[Dan Robinson]

Flow restrictors dude....simples.

 

[newbuildinstaller]

Flow restrictors dude....simples.

half open tap simplesers

 

[Dan Robinson]

God bless Eco boiler installs eh?

 

[newbuildinstaller]

god bless us all