On 14/12/2018 08:04, Jim K.. wrote:
Tim Watts Wrote in message:
On 13/12/2018 17:49, Caecilius wrote:
I'm doing a house renovation, and the hot&cold water feeds to the
showers in the bathroom and ensuite are in 15mm copper. I want to
upgrade to 22mm where possible to get better flow, as the hot water is
from a cylinder with header tank.

My view is that I'd rather install 22mm everwhere where it won't be
easy to replace later, like underneath tiled floors, and behind tiled
walls. There will still be some runs in 15mm (or maybe half inch, as
some of the pipework is very old), but I might replace these
eventually.

Is this a reasonable thing to do? Are there any reasons why I
shouldn't install 22mm where possible (apart from cost, which is not a
huge factor when looking at the whole job)?


It wasn't uncommon to run 3/4" (pre-historic version of 22mm) for both
hot and cold from the tanks to quite close to the points of use.

IIRC our bath might have had 3/4" right to the taps (bath taps are
usually 3/4" threads rather than 1/2" more common on basins)

The only disadvantage is that you have to shift more water to run the
hot though - though with a tank, you can add a circulation device which
primes the pipe - rare but exists in places where the owner is big on
not wasting water.


...but small on not wasting energy :-)


The circulation pump would normally be on a timer.

Although for filling a bath then there is the old fashioned way of
putting in the plug, turning on the hot tap and letting the first few
litres of cold water go into the bath before the hot water arrives and
mixes with the cold water.

--
Adam