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Doctor Drivel Doctor Drivel is offline
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Default combi DHW supply/flow pipe size


"olo" wrote in message
oups.com...
Also hot water takes longer to come through a 22mm pipe - the volume of
the
pipe is proportional to the square of the radius (or diameter), the flow
rate to some lesser power. This means it's brill once the hot water has
arrived, as the flow is larger, but there's a longer period flushing out
the
cold.


Fair point.

Considering all opinions so far - how about 22mm dedicated cold supply
from stopcock to boiler and then 15mm from boiler to shower/taps. This
will minimise pressure drop on the cold side and give shortest waiting
time for the hot water.


Sounds good. Have the shower hot back to the combi and cold top the shower
taken off the combi just before the cold inlet. Have a shower mixer with
pressure equalisation valve inside. Or fit one at the combi on the two
shower lines.