Audel HVAC Fundamentals, Volume 2. Heating System Components, Gas and Oil Burners, and Automatic Controls, James Brumbaugh 
Audel HVAC Fundamentals, Volume 1. Heating Systems, Furnaces and Boilers, James Brumbaugh 
Audel HVAC Fundamentals, Volume 3. Air Conditioning, Heat Pumps and Distribution Systems, James Brumbaugh