Re- plumbing mixer shower oct 9th

[WILLWONKER]

I have now got myself a mira comiforce 415 pressure balancing mixer shower.On reading the specifications as regards water pressure, ie min/max maintained and static, my Q is, as i have to incorporate in line servicing valves in hot and cold do these valves increase or decrease pressure with their small bores. thankyou.

[scotman]

Any restriction in the pipework will reduce the available pressure once steady flow conditions have been established.

[buildersmate]

Or put another way, any restriction such as a normal line valve will reduce the dynamic pressure (that when the water is actually flowing) received by the inlet to the Mira unit, though it doesn't change the static pressure (that when no water is flowing).
A way to prevent this is to fit full-bore valves - more expensive but perhaps worth it on a shower supply.

[WILLWONKER]

Thank you both for your helpfull answers, BM,when you say full bore valves, do you mean the common gate valve.