Getting myself ( as usual) overly complicated in my planning for the plumbing. The DIY component is going up all the time because the plumber we had booked in to do the work is off long term sick and has decided to retire. So we are recruiting a new plumber (see previous post about Viessman boilers) but meanwhile the build must go on so I will probably be doing the majority of the non-CH plumbing apart from installing and commisioning the boiler. [Could end up doing the CH as well, but first things first.]
[Possibly there will be queries about equipotential bonding and plastic pipes to follow.]Anyway, plastic 22mm cold water supply from the polypropylene mains to the boiler in the first floor airing cupboard.
This will run past most of the locations for cold water feeds to basin taps, showers, and toilets.
So as I see it I have two options:
(1) Tee off the 22mm as it goes past each location - this gives a neat short overall pipe run with a lot of takeoffs from the feed to the boiler. However there is the potential for a pressure drop along this feed as hot and cold taps are turned on together, and toilets are flushed.
(2) Run a seperate 22mm or 15mm cold feed alongside the feed to the boiler all the way back to the incoming main. This may reduce the pressure drop in the hot water system when cold taps are used - which is the bane of mains pressure systems such as electric showers and combi boilers.
More pipe, more complicated, but is it worth the effort?
Cheers
Dave R