Can anyone advise - I have a 50 gallon tan in the loft which has two
outlets - one provides the feed to the cold side of the pump for the shower
and the other feeds the hot water cylinder. If many showers are had one
after the other the hot supply appears to run out - however the cold water
tank is still 2/3 full and the cold feed is therefore still happy. I am
concluding that the problem is the rate at which the cold water tank can
replenish the level in the hot water cylinder as the feed from the cylinder
is pumped and the feed in is not (i.e. gravity from the cold water tank).
To make matters worse their is one section of pipe between the loft tank and
the cylinder which rises about 12" and falls - this, I would imagine is air
lock inviting - but I cleared the airlock originally present.

The obvious answer would seam to be to reroute to eliminate the raised
pipework and possible airlock but would this still get around the basic fact
that the pump will always draw water from the cylinder (41 gallons by the
way) faster than gravity will feed it?

Any advice welcome - I realise these are fairly basic questions....

John