The HVACR technical training Series HVAC Maestroâ„¢ has a new DVD available on gas furnaces. This video includes installation, start-up, and troubleshooting information on several different types of gas furnaces, including direct spark ignition, hot surface ignition, hot surface pilot ignition, and spark-to-pilot ignition. An emphasis is placed on understanding the sequence of operation. According to the company, this volume can help installation technicians understand the diagnostic procedures required of a service technician.