Learn to analyze, design, install, commission, and troubleshoot residential and commercial HVAC systems using real engineering methods and practical examples. 17 modules from fundamentals through certification, 9 complete real-project design packages (residence, apartment, office, school, hospital, hotel, warehouse, manufacturing plant, data center), a 12-template documentation kit, and a certificate of completion. One-time purchase, no account required.
Explore the Full Curriculum →Yes. EPA Section 608 certification is required by federal law for anyone who maintains, services, repairs or disposes of equipment that could release refrigerants. It comes in Type I, II, III and Universal.
NATE (North American Technician Excellence) is the leading independent HVAC technician certification. You pass a Core exam plus a specialty (installation or service) in areas like air conditioning, heat pumps and gas heating. It is voluntary but widely recognized by employers.
HVAC design engineers follow the FE Mechanical → ~4 years of experience → PE Mechanical (HVAC & Refrigeration depth) → state-board licensure path.
In most states, yes — a journeyman, master or contractor HVAC/mechanical license is required to install and service systems, typically after documented experience. Requirements vary by state and locality.
Why a cooling coil does two different jobs at once — dropping dry-bulb temperature (sensible) and condensing moisture out of the air (latent) — and why two coils with identical total BTU/hr capacity can leave a space feeling completely different.
Why relative humidity changes with temperature alone even when the actual moisture in the air never does — and why dew point, not RH, is the number that tells you how much water vapor is really there.
Why static pressure and velocity pressure trade off through a duct system — and why doubling a fan's speed doubles airflow but quadruples pressure and needs eight times the power.
Why a space can have a high air-changes-per-hour number from aggressive recirculation while still under-ventilating with the actual outdoor air ASHRAE 62.1 requires.
Why a fan sized only against the ductwork's pressure drop can fail to deliver its design airflow — external static pressure deliberately excludes the equipment's own internal filter, coil, and cabinet losses, but the fan has to overcome both.
Why an AHU sometimes skips the compressor entirely by opening its outdoor air dampers instead — and why a dry-bulb-only economizer control can be fooled by cool-but-humid air that actually carries more total heat than return air.
Why a fan curve only tells half the story — static pressure is what actually gets overcome pushing air through a duct system, velocity pressure exists only because the air is moving, and total pressure (their sum) is a genuinely different number from either one alone.
Why a Constant Air Volume system reduces cooling by reheating a fixed volume of already-cooled air — spending energy twice — while a Variable Air Volume system just delivers less air, which is why VAV has become the dominant choice for most modern multi-zone commercial buildings.
Why refrigerant never leaves the rooftop in a DX system and never leaves the chiller plant in a chilled water system — and why only chilled water, never refrigerant, travels through the building to serve many zones from one central source.
Why Bypass Factor (a coil's own physical design) and Sensible Heat Ratio (the space's load) aren't two names for the same thing — and why matching a coil's BF to a space's target SHR, not just sizing on total tons, is what correct equipment selection actually requires.
Why a unit's SEER rating (efficiency averaged across a whole cooling season) can look great while its EER (efficiency at one fixed 95°F condition) is unremarkable — and why heat pumps need a third number, HSPF, just for the heating season.
Why a compressor that can only run at 0% or 100% overshoots and undershoots the building's load on every cycle — and why adding a low stage, or continuous modulation, is what actually closes that gap.
Interactive 14-section ASHRAE reference guide covering psychrometrics, cooling/heating load calculations, duct sizing, refrigeration cycle, chillers, VRF systems, ASHRAE 62.1 ventilation, and energy codes. First 3 free to preview.
Interactive 39-chapter illustrated guide covering system fundamentals and psychrometrics, residential and multi-family systems, commercial and industrial plants, VAV and chilled-water distribution, ventilation and energy recovery, BAS controls, equipment schedules, and troubleshooting. First 3 free to preview.
Interactive 30-chapter guide following a single 45-story high-rise case study through a complete 17-phase HVAC engineering workflow — Basis of Design, central plant, airside/ductwork, hydronic risers, smoke control, BAS architecture, data center cooling, energy management, ASHRAE Guideline 36 sequences, and commissioning. First 3 free to preview.
Zoomable 17-sheet single-family residence HVAC construction drawing set — Manual J/Manual S load calculations, heat pump balance point sizing, floor/attic/roof plans, installation details, and control/wiring diagrams. Sheets 1-3 free to preview.