On Sun, 1 Nov 2009 01:33:21 -0700 (PDT), delboy wrote:

my girlfried has just moved house she has got a large hot water tank
which contains two immersion heaters.
Can we link these to a timer or do we need seperate timers?

Usually, one is to heat the top, to provide a limited amount of water for
economy reasons, whilst the second heats the whole tank.
Connecting them together, to a single timer, would obviously negate this option.

Andy C