On 9 Oct 2006 05:24:26 -0700 someone who may be "Spat"
wrote this:-

Currently my bath has a mixer tap, hot from tank, cold from mains. If I
turn the cold on full (with the hot still on) it runs cold (obviously)
but the hot then takes a good while to come back, could this be due to
high pressure cold forcing the hot back to the tank,

Likely.

and is this a problem?

Is the shell of your hot water cylinder designed to take mains
pressure? Probably not and if that is the case then you run the risk
of a spectacular failure of the cylinder one day, with some or all
of the contents of the cylinder escaping.

I was planning to pipe cold from the header tank, is there any
alternative so i can use the mains feed,

Why would you want to use a main feed?

Whoever installed the mixer did a shoddy job. At the very least they
should have put a check valve in the appropriate place.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54