"Jim Hatfield" local@localhost wrote in message
...
On Tue, 9 Mar 2004 21:23:02 -0000, "IMM" wrote:

Firstly, a combi is a "combination" of the heating and water system in
one
case, eliminating external tanks and cylinders, and generally supply hot
water at high main pressure.

Does this mean that all the radiators are at mains pressure?

No, not at all. The hot water and the rads are separate.

If so, does changing from a conventional system
to a combi mean replacing all the radiators?

No.