On Fri, 23 Jun 2006 13:44:33 +0100, "TheScullster" wrote:

All I can think of is to tie up the ball valve in the heating header tank
for a short while and monitor the water level closely. Not sure that this
will highlight leaks which are just big enough to cause pressure loss in
heating system though.

Could you substitute air for water, and do a drop test, or some such?

Thomas Prufer