Book excerpt: Aaron Jebin and Anderson Jerin, both holding Bachelors of Technology degree, in Mechanical Engineering. Both have vast experience in the field of Heating Ventilation and Air Conditioning. Aaron has worked on multiple design projects for various HVAC installations. Anderson is working as a design engineer in a leading boiler plant in India. The authors have put in extensive research to make sure this book is up to the latest standards. However, we are always open to receive constructive criticism, for the improvement of any future work, or for our personal growth. The aim of this book is to provide basic knowledge about Refrigeration and Air-Conditioner to various people. This is possible because of the vast research the authors have done before starting this work.