Plumbing for new shower

[miles]

Hi

As part of a house renovation, I am fitting an en-suite bathroom in the attic. Most of the Walls are down in the house so I can run pipe pretty much anywhere. There is a main bathroom on the floor below fed from an invented cylinder by 22mm pipe.

Is there much difference in shower performance between

• extending the 22mm pipe from the existing bathroom to feed the new en-suite;

• running a dedicated feed from the cylinder to the en-suite;

• replacing the 22mm pipe with say 25mm to feed both from one run;

(Assumimg the same is done with the cold feed)

I want to make sure I get it right before everything is covered over.

Also, another question. Is it worth having a separate 15mm pipe to feed the toilet cisterns rather than off the bath cold pipe? In a previous flat, we suffered badly from toilet-flushing messing the shower up, which I want to avoid - but not sure if it will actually be an issue this time round or if I am just being paranoid!

Thanks

Miles

[devonsteve]

Where is your cold water tank located? , it needs to be at least one metre above the shower outlet to give enough head to feed a thermostatic shower , i also believe the cold supply should be from the cold water tank , not from the mains as the loo probably is, so that hot / cold pressures are similar at the mixer A shower pump may be needed here Steve

[miles]

It's an unvented hw system so all mains pressure and no cold tank.

Thanks miles

[devonsteve]

whoops sorry Miles try spellchecker next time , your original post read invented and misunderstood you lol Dont worry , a plumber will be along here soon i guess Steve

[miles]

Oops! glad I am not the owner of an "invented" system - sounds very suspicious!

[jim]

fitting thermostatic shower valves should sort out any (disastrous) too hot/cold consequences of someone flushing somewhere mid your shower... pressure changes when bogs flush will probly be inevitable though...

cheers Jim