IA HVAC study guide
IA HVAC · Work through your exam, one topic at a time.
The IA HVAC credential is aimed at irrigation and landscape-water professionals who specify, install, or service the heating, ventilation, and air conditioning equipment that protects pumps, valves, controllers, and backflow assemblies from freezing, overheating, and condensation. It tests whether you can reason about a small mechanical room the way an irrigation designer reasons about hydraulic zones: psychrometrics, load calculation, heating and cooling equipment, air distribution and ventilation, controls and electrical safety, commissioning and troubleshooting, and the codes and efficiency rules that govern the work. The IA HVAC study guide has 10 sections and about 3,298 words.
01HVAC Fundamentals and Psychrometrics
This domain tests whether you can describe moist air quantitatively: reading the psychrometric chart, converting between dry-bulb, wet-bulb, dew point, relative humidity and humidity ratio, and turning those properties into sensible, latent and total load numbers. Q sensible = 1.08 x CFM x delta-T (dry bulb), Btu/h.
314 words, about 2 min02Load Calculation and System Sizing
This domain tests the calculation chain from envelope to selected equipment: ACCA Manual J loads, Manual S equipment selection, Manual T terminal selection and Manual D ducts. Expect questions on design conditions, load components, and the consequences of oversizing.
346 words, about 2 min03Heating Systems and Equipment
This domain covers furnaces, boilers, heat pumps and resistance heat: efficiency ratings, airflow verification, combustion air and venting, and how heat pumps balance capacity against building load. AFUE is seasonal efficiency; input x AFUE = output.
341 words, about 2 min04Cooling Systems and Refrigeration Cycle
This domain tests the vapor-compression cycle, refrigerant behavior and field verification of charge using superheat and subcooling rather than pressure alone. Four components: compressor, condenser, metering device, evaporator; four processes: compression, condensing, expansion, evaporation.
314 words, about 2 min05Air Distribution
This domain tests how air actually moves through the system: fan performance, static pressure budgets, and the delivery characteristics of terminals and diffusers. Fan laws: CFM varies with RPM, static pressure with RPM squared, brake horsepower with RPM cubed, at constant air density.
315 words, about 2 min06Duct Design and Ventilation
This domain covers duct sizing methods, pressure loss in fittings and flexible duct, and the outdoor air calculations that set ventilation rates in commercial and residential work. Common sizing methods: equal friction, static regain and velocity reduction.
371 words, about 2 min07Controls
This domain tests control sequences and the logic behind them: thermostats, economizers, demand-controlled ventilation, static pressure reset and the point types used in building automation systems. A thermostat has a deadband; proportional and PID loops trade offset against stability.
326 words, about 2 min08Electrical and Safety
This domain tests electrical fundamentals applied to HVAC equipment nameplates and the safety practices that surround service work. Ohm's law and power relationships: V = I x R, P = V x I, with a power factor for alternating current, and three-phase power using the square root of three.
357 words, about 2 min09Commissioning, Maintenance and Troubleshooting
This domain tests the process of proving a system works as designed and the diagnostic order used when it does not. Commissioning starts from the owner's project requirements and basis of design, then pre-functional checklists, then functional performance testing, with a test and balance report and an issues log.
306 words, about 2 min10Codes, Standards and Energy Efficiency
This domain tests which document governs which decision, and how efficiency ratings translate into real energy use. ASHRAE 90.1 covers commercial and high-rise residential energy; the IECC and ASHRAE 90.2 cover residential.
308 words, about 2 min