Most of the work technicians routinely perform is in maintaining existing equipment as opposed to installing new systems. The procedures and visual observation conditions presented in this title will enable technicians to perform their tasks more effectively. By knowing how the equipment is designed, built, and how the materials behave over time, they will be better able to execute a maintenance program extending equipment life and reducing unplanned malfunctions. This book's emphasis is on implementing these actions correctly and in a timely basis so that equipment experiences an increase in "life expectancy," reliability, more efficient energy performance, and a reduction in the possibility of future failures and liability. While the main focus is on equipment installed in residential homes, the procedures detailed certainly apply to larger commercial heating equipment as well.