Hi Christian,
I'm contemplating much the same exercise (power shower in the distant
future) hence
I'm interested in this thread):

"Christian McArdle" wrote in message
t...
I am taking a dedicated feed from the cold water tank in my loft and then
teeing into the hot water supply. Is this best practice?

The main issue is one of sucking air through the hot water cylinder vent
pipe. It is standard practice to have a separate tapping in the cylinder
for
the shower called a flange. There are several types.

However, you can sometimes get away with using the standard hot water
outlet. If this is to work, you need to have a good flow rate from the
cold
header tank into the cylinder. This is helped by having large bore pipe
(at
least 22mm) from a tank sitting directly above with flowed bends rather
than
elbows and full bore valves. At the other extreme, it is unlikely to be
successful if you have 15mm pipe flowing halfway round the house to the
cylinder with inline isolator ball valves and elbows aplenty.

So you wouldn't envisage much problems with a 28mm feed to the hot tank from
the loft cold storage and a 28mm output which could be teed for the power
shower?



It is easy enough to see if it works first and then fit a flange if you
get
air in the pump (or upgrade a seriously deficient but easily accessed
cylinder cold tank supply).


The symptoms of sucking air being what apart from the noise ?

Mungo