I've taken and passed the PE exam, HVAC afternoon section, this October. I did take the School of PE prep class which helped to focus on the needed materials. Know your conversions, understand heat exchanger problems (air to air, water to air, water to water). Exam taking Strategy: focus on your stengths. Do three passes of the exam. 1st- do only the easy ones in 30 sec or less no computations, 2nd do the computation problems you know, 3rd do the hard problems. A lot times on your 1st pass you might not know how to approch hard a problem but as you take the exam other problems can trigger ideas.