PE Mechanical HVAC study guide
PE Mechanical HVAC · Work through your exam, one topic at a time.
The Principles and Practice of Engineering (PE) exam in Mechanical: HVAC and Refrigeration is one of more than 20 PE exams administered by NCEES, the body that writes and delivers the exams used by U.S. state licensing boards. The PE Mechanical HVAC study guide has 7 sections and about 2,181 words.
01Basic Engineering Practice
Basic Engineering Practice is the "everything else" domain: units and dimensional analysis, engineering economics, statistics and uncertainty, codes and standards, project delivery, and professional ethics. Questions are usually short and deceptively simple, so the real skill is disciplined unit tracking.
330 words, about 2 min02Thermodynamics
The First Law is the backbone: for a closed system, Q − W = ΔU; for a steady-flow open system, q − w = Δh + Δke + Δpe. Because HVAC equipment is almost always open flow, work with enthalpy , not internal energy.
316 words, about 2 min03Psychrometrics
Every psychrometric question hinges on seven linked properties: dry-bulb (DB), wet-bulb (WB), dew point (DP), humidity ratio (W, lb moisture per lb dry air), relative humidity (RH), enthalpy (h), and specific volume (v). On the chart, DB is vertical, W is horizontal, and the saturation curve is the boundary above which nothing exists.
338 words, about 2 min04Fluid Mechanics
Continuity (ṁ = ρAV) plus Bernoulli/energy for ideal flow, corrected by head loss, covers most questions. Reynolds number Re = ρVD/μ (≈ 4,000 for transition in pipes) separates laminar from turbulent, and Darcy–Weisbach (h f = f (L/D)(V²/2g)) or Hazen–Williams gives friction loss.
316 words, about 2 min05Heat Transfer
Conduction uses q = kAΔT/L; convection q = hAΔT; radiation q = εσA(T1⁴ − T2⁴). Build thermal resistance networks in series and parallel: R cond = L/kA, R conv = 1/hA, R rad = 1/h r A.
290 words, about 1 min06HVAC Systems
Cooling loads come from conduction through the envelope, solar gain, internal gains (people, lights, equipment), infiltration, and ventilation. Use CLTD/CLF or radiant-time-series methods, but always account for fan heat and duct gain as part of the coil load.
313 words, about 2 min07Refrigeration Systems
Four processes: isentropic-ish compression (1→2), constant-pressure desuperheating, condensation, and subcooling (2→3), isenthalpic expansion through a metering device (3→4), and constant-pressure evaporation with superheat (4→1). Capacity is the mass flow times the enthalpy rise across the evaporator: Q = ṁ(h1 − h4).
278 words, about 1 min