Book excerpt: Depending on what part of the country that you reside in, gas-burning heating systems can be either an absolute necessity or a rarity. For those that maintain, service and install gas heating systems or those just looking for a more in-depth source of accurate information, this modular training program focuses on furnaces and boilers that burn natural gas or LP. The combustion of gas to generate heat can be dangerous and should be thoroughly understood by HVAC technicians. This program covers many facets of gas heating including: combustion, system components and controls, heating sequences, installation, and troubleshooting. Through advancements in technology, modern heating systems have become far more efficient than their predecessors. Integrated circuit boards and electronic ignition systems have replaced the mechanical controls and manually lit pilots of older systems. Today, technicians may encounter furnaces or boilers that are older than they are, complex high-efficient systems, or anything in between. It is critical that they have a working knowledge of all these systems. This manual provides students and practicing technicians with the information and knowledge necessary to safely work on systems that incorporate gas combustion to provide heat. The information to service, maintain, and install these systems is also presented in an easy-to-understand format. The manual is full of color images and diagrams and includes end-of-chapter worksheets. Gas Heating was written to be a primary text that focuses specifically on gas-burning heating systems which can be used as a stand-alone text or a supplement to your current text book.