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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> full bore flexible 15mm hose? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1265136244 Message started by londonman on Feb 2^nd, 2010, 6:44pm

Title: full bore flexible 15mm hose?
Post by londonman on Feb 2^nd, 2010, 6:44pm

Does such a beast exist? I'm going to be plumbing in a power shower pump and it will be easier if I convert the 22mm pipe down to the 15mm inlet that the pump needs if I use flexible hose. But in my experience the bore of these is a bit small and so I was thinking that that would impair the flow of the shower.

Title: Re: full bore flexible 15mm hose?
Post by thescruff on Feb 3^rd, 2010, 4:51am

"Speedfit" pipe is flexible, and 15mm ;D

Title: Re: full bore flexible 15mm hose?
Post by londonman on Feb 3^rd, 2010, 12:17pm

Yup..I know..but it's the internal bore that concerns me. Most of the flexible hoses seem to have the internal bore reduced down to about 10mm which seems to me to make the flow of water in the shower restricted. Spedfit advertise a FullBore 22mm flexible hose but I couldn't find any 15mm equivalent.

EDIT: I'm clearly misunderstanding something regarding shower pumps and flows. It's a Stuart Turner Showermate and in their instructions clearly state to bring the pipework close to the pump using 22mm. Just looked in the box and they supply flexibles to go into the pump and guess what? They are Speedfit - 15mm - with the dinky 10mm internal bore size....so why 22mm for the rest of the way? Seems to suggest to me that I don't need to worry about the internal bore size of any flexibles I might introduce.

Title: Re: full bore flexible 15mm hose?
Post by Lectrician on Feb 3^rd, 2010, 8:53pm

As far as I know, pressure is affected by the length of pipe, the number of bends and the internal diameter.

This is why they would like the 22mm to end as close to the pump.

Title: Re: full bore flexible 15mm hose?
Post by CWatters on Feb 3^rd, 2010, 9:36pm

londonman wrote on Feb 3^rd, 2010, 12:17pm:

EDIT: I'm clearly misunderstanding something regarding shower pumps and flows. It's a Stuart Turner Showermate and in their instructions clearly state to bring the pipework close to the pump using 22mm. Just looked in the box and they supply flexibles to go into the pump and guess what? They are Speedfit - 15mm - with the dinky 10mm internal bore size....so why 22mm for the rest of the way? Seems to suggest to me that I don't need to worry about the internal bore size of any flexibles I might introduce.

It seems to be the same with shower waste traps. I tried everywhere to find a 2" top access trap for a high flow rate shower. They all narrow down to something like 1.25" and have adaptors to get back out to 2". Even traps designed to fit a 90mm diameter hole in the shower tray seem to have a small hole where it matters.

Title: Re: full bore flexible 15mm hose?
Post by thescruff on Feb 4^th, 2010, 12:52am

Lectrician wrote on Feb 3^rd, 2010, 8:53pm:

As far as I know, pressure is affected by the length of pipe, the number of bends and the internal diameter.

This is why they would like the 22mm to end as close to the pump.

Size affects volume and not pressure.

The reason you take 22mm as close as possible to the pump is to avoid starvation. Gravity in pumped pressure out, so you need to avoid more trying to get out than can get in.

Title: Re: full bore flexible 15mm hose?
Post by Zambezi on Feb 4^th, 2010, 8:38am

Screwfix do some 12 or 13mm bore flexis.