Shower pump pipework

[Justin]

Following on from my last post, I have decided to leave the existing pipework at 15mm from just after the shower pump to the shower head. I'm using Hep2o 15mm pipe in the roof void which means there will be no joints or sharp angles in the pipe run.

However in the airing cupboard where the pump is I'm trying to keep the pipework as tidy as possible. At this point it is still 22mm. I'm using copper pipe here with compression joints.

To get a really neat pipe run along a wall I would have to introduce another

2 90 degree compression joints, on top of 2 others, making 4 in total on both the hot and cold pipes.

What I'm wondering is whether adding 2 extra 90 degree bends will have any appreciable difference on the shower performance ? Its a 2.2 bar Salamander.

[John Stumbles]

In calculating the resistance of pipework to gas flow a 90 degree knuckle/elbow is reckoned equivalent to 0.5m of straight pipework. I guess it'd be the same for water flow.

FWIW I've a booster pump in my attic, sitting at the same level as the base of the cw storage tank (i.e. about the worst possible position since pumps like to push, not pull) and 15mm plastic pipework from cw tank & hw cylinder to pump and pump to shower - perhaps 3m each side of the pump for the hot, bit less for the cold - and the blast from the shower head is still like a water cannon. The pump is just a wimpy low-end watermill. It's a fairly small shower head though - if you're driving a watering can rose or a body panel with multiple sprays and jets then the higher flow rate will make the resistance of the supply pipework more significant.

Oh, and changing the flexible hose connecting to our shower head, from about

6 or 8mm bore to 11mm, turned it from pretty pathetic into industrial grade.

[Justin]

I'll go the neat route I think, couple of extra bends shouldn't hurt seen as its a decent pressure pump to start with. Don't know what I'm worrying about if your set up gives good performance. I';; only be powering a shower head!