Concepts
Core HVAC concepts: the refrigeration cycle, heat transfer, psychrometrics, electricity, combustion and airflow.
Building Science
Static Pressure and Duct Diagnostics
Measuring total external static pressure and using it to find where a duct system is choking.
Concepts
Air Filtration
Filter ratings, the trade off between filtration and airflow, and how filters actually fail.
Concepts
Humidity Control
Why humidity matters as much as temperature, and how equipment adds or removes moisture.
Concepts
Duct Leakage and Building Envelope
What leaky ducts and a leaky envelope cost, and how each is measured.
Concepts
HVAC Fundamentals
Heat Transfer
Conduction, convection and radiation, and why every HVAC system is really a heat moving machine.
Concepts
The Refrigeration Cycle
How a vapor compression system moves heat from where it is not wanted to where it can be rejected.
Concepts
Superheat and Subcooling
The two measurements that tell you how a refrigerant circuit is really being fed and drained.
Concepts
Temperature and Heat
Temperature measures intensity, heat measures quantity. Confusing the two is the root of many bad diagnoses.
Concepts
Gas Furnace Sequence of Operation
Step by step through a call for heat on a modern induced draft furnace, and what each step proves.
Concepts
Pressure and Temperature Relationship
Why a pressure reading tells you a saturation temperature, and how technicians use that link every day.
Concepts
Ignition Systems
Standing pilot, intermittent pilot, hot surface and direct spark ignition, and how each proves flame.
Concepts
States of Matter and Phase Change
Why refrigeration uses boiling and condensing rather than simply moving warm and cold fluid around.
Concepts
Flame Sensing and Rectification
How a furnace proves flame with a single rod, and how to measure and interpret the microamp signal.
Concepts
Sensible and Latent Heat
The difference between heat you can measure with a thermometer and heat that removes moisture from the air.
Concepts
Airflow Fundamentals
CFM, static pressure and why airflow problems are behind a large share of service calls.
Concepts
Heat Pump Defrost Cycle
Why an outdoor coil frosts in heating, how the control decides to defrost, and what normal defrost looks like.
Concepts
Electricity Fundamentals
Voltage, current, resistance and power, and how they show up in HVAC line and control circuits.
Concepts
Ohm's Law and the Power Formula
The arithmetic behind every electrical reading you take, and how to use it to predict what a meter should show.
Concepts
Series and Parallel Circuits
How HVAC wiring is arranged, and why safety devices are in series while loads are in parallel.
Concepts
Psychrometrics Basics
Dry bulb, wet bulb, dew point and relative humidity, and what the psychrometric chart tells you about a coil.
Concepts
Heating and Cooling Load Basics
What a load calculation accounts for, and why sizing from square footage or the old unit causes problems.
Concepts
Comfort and Indoor Air Quality
Comfort is more than temperature. Humidity, air movement, filtration and ventilation all shape how a space feels.
Concepts
Single Stage, Two Stage and Variable Capacity
How staged and modulating equipment differs from single stage, and what that means for comfort and setup.
Concepts
Refrigerant Types and Handling
Blends, glide, safety classifications and why you never mix refrigerants or charge a blend as vapor.
Concepts
Combustion Basics
What clean combustion requires, what the products of combustion tell you, and why analysis beats guessing.
Concepts
Installation
Duct Design and Airflow Delivery
Sizing, friction, fittings and the reasons a duct system fails to deliver what the equipment can produce.
Concepts
Venting and Draft
Vent categories, why draft matters, and the failures that put combustion products into the building.
Concepts
Combustion Air and Makeup Air
Why fuel fired appliances need a reliable air supply, and what happens in a tight building without one.
Concepts
Gas Piping and Gas Pressure
Supply and manifold pressure, sizing for input, and safe practice around gas connections.
Concepts