This is mostly stuff relating to boilers, furnaces, radiators, and similar heating equipment, but I know much of it will also appeal to the nostalgic interests of ECN membership. There is even a complete scan of the 1949 Bell & Gossett heating handbook!
http://www.heatinghelp.com/library.cfmThere are some files in the library which do also cross over to electrical matters to some degree. Check the brief history of district steam heating from Detroit Edison's power plants, or the range of thermostats and other heating controls available from Honeywell.
