Not a very good book. The author James E. Brumbaugh must be recycling his information from the 1st edition. This book is very old school. The pictures are in black and white and seem to be recycled pictures from HVAC theory back in 1960's era.I would not recommend purchasing this book. I hope the author's next edition will be in color with more "new school" information such as a "Puron" refridgerant techology, modern day HVAC servicing procedures such as "EPA Section 608" information, and more up to date pictures - take pictures of new housing and commercial construction, factory workers putting units together, and a technician working on a actual unit. James E. Brumbaugh is very "old school".