what sort of shower pump do i need

[zooankski]

I intend to fit a new power shower in our ensuite and would like some advice of pump spec.
I want to place the pump in the airing cupboard on my landing.
Hot water will be drawn off of the top of the cylinder which is also in the cupboard and the cold supply from the tank in the loft.
The problem is that i need to use the existing shower pipework which is also in the loft and so the pump would need to push the supply from the airing cupboard floor level back in to the loft and then down to the shower.
I had thought about taking up the landing boards and going direct and up to the shower but the work required would be horrendous.
Would a positive head pump work in this situation bearing in mind the shower pipework in the loft sits only about 2' below the old water tank or should i go for a negative head pump?

 

[Richard C]

You don’t need a negative head pump, any suitable positive head pump should do you; I would recommend a minimum 2 bar pump, in many cases 1.5 bar can give disappointing results; it’s really down to how much is in your wallet.

The only problem with using existing pipe work is it’s usually only 15mm & if you are fitting a drencher head or any high capacity shower you really need 22mm feed pipes. Any isolator or gate valves in the run should also be full bore or these will restrict the flow even further. For the hot feed you must use either an approved anti-aeration flange or a 45 degree angled take off from the vent or you will get problems & could damage the pump. You will need vents at the tops of the pipe loops or air residue will build up & eventually air lock the pump.

Hers a link to an installation guide; all pump manufacturers have their own but this is one of the most useful I know in terms of explaining the different pump types & systems;

http://www.salamanderpumps.co.uk/Download/instructions.pdf