Go to google click "more" on the various google choices....then click books...

once in books type in your search words and search...

or go here.....lol

http://books.google.com/bkshp?ie=UTF...l=en&tab=wp&q=

Quite a few books on early hvac....sheetmetal layout, boilers and steam heating....early refrigeration...nothing new there ...mostly 19th and early 20th century books.... but they are interesting.... ammonia and carbolic acid refrigeration was the subject of one book....lots of old drawings and stuff in these books...

downloadable in pdf

Or books on about any subject... I actually went there looking for some older books on carpentry and woodworking....I like doing things the old ways with hand tools and not expensive machines... but I got to looking around and found many interesting books on boilers...steam etc... I cant read on the net but I only need specific info on certain things...so I can download 20-30 pages of specific reading...

you can also search "project gutenberg"...another collection of books.... but it didnt contain a lot of "technical" books when I was looking around there a couple of years ago.