Thickness of Flexible Tap Tails

[Deleted member 126887]

I recently purchased monoblock bath taps with shower extension. It came with 3 flexible pipes - one for the shower (approx 13mm diameter outer pipe) and two smaller ones for hot+cold approx 10mm.

I noticed the flow is a bit less when it's only using hot or cold. Will it help if I replaced the 10mm inlets with larger 13mm pipes - even though the actual push-fit threading (with double o-ring washers) will still be 10mm?

In other words, will flow be faster if the majority of the pipe is larger, but the end of the pipe (the thread) is the same size?

Thanks.

 

[Timmy D]

No noticeable difference.

 

[Roy_66]

Silly question: Is your hot water system pressurised or gravity fed from header tank(s) in the loft. If you are unsure please don't risk going in the loft unless you are fully confident what you are doing etc etc Instead I'd find a professional plumber.

For a length of pipe flow will be dependent on the cross sectional area and inversely proportional to the length of pipe:

Flow Rate Vs. Pipe Size

According to Poiseuille's Law, the flow rate through a pipe at constant pressure and temperature varies with the fourth power of the pipe radius.

sciencing.com

I would guess though the issue is the supply pressure. On the box for the monoblock or in the instructions or online does it say what water pressure is expected?

If you have an old fashioned gravity fed system from header tanks then some 22mm feed pipes to traditional large bore taps might help.

Cheers,

Roy (amateur, very)

 

[Deleted member 126887]

I've completed it now. There's no other product that exists other than m10 thread with 8mm bore.

It's a tiny bit slower than 10mm bore but not the end of world.