I found this site some time ago - not done anything with it - but others may find it useful for reference purposes...On another issue - MrFLuffy, sounds like an interesting heating set-up you have. How about a new thread and some pictures of what you've done.....with some welding content of course.
I'm hankering after retirement from my job which may then mean a bit of domestic downsizing and a hot water and heating system that combines gas, solid fuel and solar.
http://www.navitron.org.uk/index.htm