installing new bathroom need advise Drainage and wastage systems and plumbing help, advice and answers

[jond]

Hello to all plumbers out there need advise on best way of running mains water pipe to combi/condensing boiler i am going to refit my bathroom in my two bed terrace the mains 15mm pipe runs up from my kitchen and through my bathroom exposed i intend to pull floor boards up to lay the pipes under and as to not having them visable can i run the toilet supply off the 15mm pipe before it goes to the boiler or is this not advisable due to the boiler and also the cold water supply that comes back into bathroom after it goes to the boiler is 15mm then changes to 22mm i was going to get rid of the 22 and just use 15 but would this afect the flow rate any advise gratefully received

[htg engineer]

Getting rid of the 22mm pipe is actually best, for best performance the hot water pipe should be 15mm from boiler to all outlets, as it is 15mm mains entering the boiler.

The way the pipes are connected doesn't matter that much, teeing the toilet in before the boiler shouldn't affect the boiler.

[jond]

Thanks for the quick response so does this mean i could run the bath and shower points of the mains before it goes to boiler? Also the shower is going to be a mixer shower seperate from the bath taps termostaticly controled are they any good and will it run good with my combi/boiler that is a baxi platinum 28he here is some technical info on boiler if it helps max continuous dhw flow rate rasied 35 degrees c 11.5litres/min + min dhw flow rate 2litres/min + min operating dhw pressure 0.15bar and max is 8 bar thanks for your help

[htg engineer]

The boiler should be capable of providing a decent shower, I have just fitted a new bathroom in my house and got rid of the electric shower and fitted a thermostatic mixer shower.

Take a look at Mira Excel, Bath Shower Mixer - brilliant product not like the old bath shower mixers. I fitted one in my house and it's brilliant (also saves on pipework and chasing walls to hide the pipes for a wall mounted shower)

Teeing in alot of appliances before the boiler, may cause problems when someone is in the shower as the flow rate will be reduced. But if it's just for the bathroom, you're not likely to be running the wash basin or bath when in the shower so shouldn't be a problem.