Shower & shower pump installation

[ChristinaLander]

We are installing a shower and shower pump in our downstairs utility room. We do not have a mains water supply, our water comes from a private spring and therefore the water pressure into the house is low. We will be taking the cold water supply for the shower from the tank in the loft, and the hot water supply will come from the hot water cylinder, both supplies will be using 22mm speedfit plastic pipes as far as the pump.
My question is:
1. We haven't bought a pump yet, but are considering a Stuart Turner Monsoon twin positive head pump, but don't know if a 2 bar pump will be enough, or should we go for more than this?
2. The shower valve we have bought, which is made by Roman, has 15mm feeds into the shower valve. So should we run 15mm pipe from the pump to the shower valve, or will this reduce the flow? Is it normal to use 15mm pipe into the shower valve?
I would really appreciate any advice anyone can offer me!

 

[Tibbot]

Stuart Turner Monsoon is a top pump, 2 bar is more than adequate for 1 shower. You'll need 22mm from pump to as close as feasible before it reduces to shower valve.

 

[ChrisR]

Good pumps but not the quietest, Put it on a block of concrete, and something squishy between the concrete and whatever's underneath. Several layers of carpet underlay works.

If the cistern's a couple of floors above, that'll add half a bar or so, so 2 bar is fine. You can use a couple of metres of 15mm with no real effect, remember the hot and cold eventually share a thin hose...