I've just got back from hols to find the CH expansion warning pipe
dripping and algal?sp growth on the lean-to roof as a result so it had
obviously been dripping for some time. The boiler had been off while we
were away. I decided to leave investigating until today but magically
the dripping has stopped now that the boiler has been run a few times
for hot water. Why'd that happen?

--
dave @ stejonda