Just glancing at my bookshelf the HVAC books I use: ASHRAE Fundamentals (Applications, Systems and Refrigeration), ASHRAE 62, ASHRAE 55, ASHRAE 90.1, ASHRAE 15, ASHRAE 135 Building Code, Natural Gas Code, Manual of Industrial Ventilation, Mark's Mechanical, Cameron Hydraulic Data, Pipefitter's manual, SMACNA design guides, Carrier System Design Binder, B&G Engineering Design Binder, HVAC Equations, Data and Rules of Thumb.
I've also got a stack of plumbing and fire protection books... but I like books.