Hot water cylinder on a vented system 900mm high by 450mm diameter, direct
version. manufacturer advises capacity 117 Ltr.

Trying to work out if a pump installed via a flange to the tank and giving
say 12 Ltrs a minute at the shower. Assume 8 Ltrs per min is hot water and
the rest made up from the cold rising main.

What is the real capacity of useful hot water from such a cylinder. I guess
say 64 Ltrs so eight minutes shower at most.

Does this sound somewhat optimistic.

Eddie