Today's furnace repair technician must be a specialist in several areas. Modern furnaces burn oil, natural gas, wood and corn. Each fuel has its own special requirements for proper heating, and a furnace repair technician must have a thorough understanding of each fuel. The National Association of Plumbing-Heating-Cooling Contractors and the Air-Conditioning Contractors of America offers an apprenticeship programs through local chapters, according to the U.S. Bureau of Labor Statistics (www.bls.gov). Apprenticeship programs generally run 3-4 years and include classroom training. Furnace repair technicians must also be proficient in sheet metal and fiberglass work so they can repair faulty furnace runs and ductwork.