Shower Problem

[bentley]

I have a couple of headaches one i fitted a salamander whole house shower pump the noise sounds like my preesure washer.Secondly i am pumping just my hot water supply round the house along with hot and cold to the shower after i turn the shower off then a couple of minutes turn it on i have no water from the shower it seems to be draining back.any ideas?

 

[Lee-King]

Non return valves on the shower supplies

 

[bentley]

Cheers Lee
It says in the manual do not use non return valves