ID HVAC study plan

Define the three legs of a heating, ventilation and air conditioning system and explain how each leg moves or removes heat

Convert between sensible heat, latent heat, Btu/h, tons of refrigeration, and kW without reference notes

Interpret a psychrometric chart to locate dry-bulb, wet-bulb, dew point, relative humidity, and enthalpy for three sample air states

Explain how sensible heat ratio determines supply air volume and apparatus dew point for a cooling coil

List the four refrigerant-side state points of a vapor-compression cycle and label them on a hand-drawn diagram

Size a heating load by summing transmission losses through walls, roof, windows, and doors using U-values and design temperature difference

Calculate infiltration and ventilation loads using air-change rates and the sensible/latent split

Compute duct heat loss and gain for a specified run using insulation R-value and surface area

Select a furnace or boiler capacity from a calculated load and justify the safety margin chosen

Explain the difference between block load and room-by-room load and when each is required

Trace the refrigeration cycle on a pressure-enthalpy diagram and identify superheat, subcooling, and the metering device state

Calculate superheat and subcooling from gauge and thermometer readings for three worked examples

Diagnose a restricted metering device, an overcharge, and an undercharge from a symptom table you build yourself

Describe compressor types (reciprocating, scroll, screw, centrifugal) and match each to an application range

Explain the function of accumulators, receivers, filter-driers, and oil separators in the circuit

Use the equal-friction and velocity-reduction methods to size a trunk-and-branch duct system for a given airflow

Convert between round, rectangular, and oval equivalent duct sizes

Select fittings and apply fitting loss coefficients to compute total static pressure for a sample system

Determine fan airflow from a manufacturer curve given external static pressure

Explain the purpose of balancing dampers, turning vanes, and manual volume dampers in a layout

Compute the hydronic flow rate and head for a boiler loop using the temperature drop and heat output

Identify the components of a hot-water heating loop and the function of each: circulator, expansion tank, air separator, zone valve, and aquastat

Compare series loop, one-pipe, two-pipe direct return, and two-pipe reverse return piping and state the balancing implication of each

Explain combustion safety checks: draft, flue gas analysis, carbon monoxide limits, and combustion air requirements

Describe steam heating basics including traps, mains, and why steam systems differ from hot-water systems

Explain the refrigeration cycle control sequence for a packaged rooftop unit from call for cooling through economizer operation

Describe the operating sequence of a gas furnace from thermostat call through ignition, flame proving, and blower delay

Interpret control diagrams and ladder logic for a fan start-stop circuit with safeties

Compare constant volume, VAV, and variable refrigerant flow systems on part-load behavior and control needs

Explain the role of economizers, energy recovery ventilators, and demand-controlled ventilation in a sequence

Calculate indoor air quality ventilation rates for a sample occupancy using ASHRAE 62.1-style rates and the multiple-zone procedure

Explain filter ratings (MERV, HEPA) and select a filter for a stated particulate target

Compute the sensible and latent capacity of a cooling coil from entering and leaving air conditions

Diagnose common air-side faults: low airflow, refrigerant undercharge, dirty coil, and duct leakage, using a symptom-to-cause table

Explain the effect of altitude and air density on airflow and capacity calculations

Re-derive the ten formulas you used most often from memory and check each against your notes

Work through timed practice problems covering load, duct, refrigerant, and hydronic calculations

Review your own troubleshooting matrices and explain each entry aloud without notes

List the code and standard references that govern ventilation, refrigerant handling, and combustion safety

Write a personal error log of every concept that still feels uncertain and schedule a targeted review of each