This text offers a complete guide to the installation, maintenance, and service of gas, oil, and electric forced warm air heating and heat pump systems. It explores—in great detail—a large base of newer as well as traditional equipment, using the principles and practices of older furnaces as a means of understanding the newer, electronically controlled, high-efficiency furnaces. It explores, in detail, the operation and diagnosis of controls—from the thermocouple to the SmartValve®—and provides a complete overview of all aspects of residential and light commercial heating.