Does size matter? (Shower hoses)

VfM4meplse

Hi all,

I recently replaced the leaky aluminium hose for my handheld shower (over bath) with a 2m hose. The previous one was 1.5m and the flow was what you'd expect, good enough but in no way comparable to my electric power shower. Since I changed to the 2m length the water pressure seems to have dropped. This is even at low heights above the tap, not just when held at full length above it.

Is this connected or pure co-incidence? If it's known that longer shower hoses lead to reduced water flow then I'll just go and buy a shorter hose. If not, what can I actually do to increase the water pressure?

TIA

rich13348

Is it possible the ID (inside diameter) of the new hose is larger than the old one. If this is so then you will have a drop in water pressure. Also the further water has to be forced up a pipe or hose the less energy it has when leaving the end of the pipe hose so that could be another contributing factor.

WobblyDog

A longer hose will reduce the flow rate (ie. litres per minute) to some degree, due to the greater surface area over which friction/drag between the water and the hose can occur.

A smaller inner diameter will also reduce the flow rate to some degree, because the water will have to travel faster for a given flow rate, increasing drag/friction.

I don't know how to quantity these effects, the maths looks quite complicated:
http://www.pipeflowcalculations.com/pipe-valve-fitting-flow/flow-in-pipes.php

But in summary, short hoses with larger inner diameters are likely to give a higher flow rate.

Le_Kirk

Is it possible that with the hose being longer, you have kinked it somehow or in the fitting of it, you have twisted it?

Head_The_Ball

There may be a flow restrictor fitted at one or other end of the hose.

Or there may be a filter that is clogged?

VfM4meplse

rich13348 wrote: »

Is it possible the ID (inside diameter) of the new hose is larger than the old one. If this is so then you will have a drop in water pressure.

WobblyDog wrote: »

A smaller inner diameter will also reduce the flow rate to some degree, because the water will have to travel faster for a given flow rate, increasing drag/friction.

I'm really confused now, as your posts are saying the opposite. Added to which I thought diameters are standard?! Logically a smaller diameter would increase flow. I shall investigate furthe

Jonesya

Shower hose diameters are not standard. You want one with the largest inner diameter possible, this means it imposes the minimum pressure drop on the water flowing through it, so you get maximum pressure at the shower head. If you shop around you can find some where they advertise the measurements and track down one with a large inner diameter.

I bought a large bore hose replacement for a shower taken off a bath mixer tap, so low pressure running off the water tank in the loft. I got about 50% more flow from the new hose compared to the old, small-bore hose.