On Thu, 24 Nov 2005 22:06:25 -0000, "altheman" alan@ford50(no
spam).freeserve.co.uk wrote:

hi, thanks for the speedy response....i am not sure if i have gravity hw or
all pumped..the set up is as follows....i have in the loft a main tank...and
a header tank....and also in the airing cupboard there is a big tank that
actually holds the hot water...not sure if that is the type of information
that will help...but personnaly i have no ideas about central
heating..sorry...thanks again

Ay it's simplest installation, the HW switch simply turns the boiler
on and the other switch just turns the CH pump on to pull the water
through the radiators.

Turn both switches off and let the boiler cool down.

Turn the HW switch on and the boiler should ignite.
Turn that off and turn the CH switch on. You should just hear the pump
whining away somewhere but the boiler won't ignite.

Thus you have an unpumped HW system with the pump turning the
radiators on.

If the second switch also turns the boiler on as well as the pump, you
will have some motorised valve in the pipework somewhere.

You really need someone mildly familiar with CH to have a look at it
and identify what does what.