On Fri, 25 Sep 2009 01:17:32 -0700 (PDT), Matty F
wrote:

On Sep 25, 7:39 pm, "Man at B&Q" wrote:
On Sep 25, 1:35 am, Matty F wrote:

We tend not to have header tanks here. I've only ever seen one, and
only because I was fixing it after a tradesman had failed. I don't
understand the need for them, since there are better and cheaper ways
of getting the pressure right.

They're not about getting the pressure right.

What are they for? Breeding mosquitoes and cockroaches and rats?
Putting lots of weight on the ceiling so it collapses?

Originally they were part and parcel of solid fuel (typically
fireback) boilers in a hot water system.

The fire/boiler held a big reservoirlot of stored heat. For safe
operation of the boiler to avoid a steam explosion a big reservoir of
stored cold water was required.

I've done away with ours, if I regret it a bit. The supply incoming to
the 1976 house is too feeble.

Derek