Doctor Drivel wrote:

wrote in message ...
A standard problem with primatic cylinders, which have an air gap within

the

cylinder to separate the primary and secondary circulations. It was easy,
particularly on solid fuel systems, to 'blow the bubble out'.


I have always regard them as an expensive waste of time. A lot of huff to
save on the cost of an F&E tank.

Hmm interesting. After a little more research I might be incorrect in
thinking it was a primatic cylinder as the system did have a F&E tank.
The cylinder did appear to have connection points where you would expect
the coil to be (but nothing was connected to them), however the feed and
return from the heating circuit were supplied via 15mm copper pipe
through where I would have expected the immersion heater to go.

When I removed the cylinder (I replaced the system with a combi), I made
a hole in the top and peered in, and could see two kind of 'bell' like
things (I think, it was dark in there!) Any idea what that was all about
then?

Cheers,
Ben