HVAC Air Distribution study plan

Define the three duct pressure regimes (negative, positive, and neutral) and map where each occurs in a supply, return, and exhaust system

Calculate friction loss per 100 ft for a round galvanized duct using the Darcy-Weisbach equation at a stated airflow and diameter

Explain how velocity pressure, static pressure, and total pressure relate along a duct run and compute total pressure from a measured velocity pressure

Convert between cfm, velocity, and duct area for rectangular and round ducts and verify results with the continuity equation

Apply the equal-friction method to size a trunk-and-branch supply layout and compare it to the static-regain method

Select fittings and note their loss coefficients (elbows, tees, transitions) and convert C values into pressure drop

Size return and exhaust paths so that system total pressure matches the fan curve operating point

Identify common duct-sizing errors such as oversized branches, abrupt transitions, and ignoring fitting losses

Distinguish constant-volume, VAV, and variable-volume zoning strategies and state when each is appropriate

Describe the function of VAV terminal units, reheat coils, and fan-powered boxes in part-load control

Explain static pressure reset control and how it reduces fan energy at part load

Calculate fan power using the fan laws for a speed change and estimate the energy effect of a reset schedule

Explain the throw, drop, spread, and terminal velocity characteristics of a supply diffuser and how they affect occupant comfort

Select a diffuser and return grille for a stated room load, ceiling height, and allowable noise level (NC)

Diagnose common comfort complaints (draft, stratification, short-circuiting) and propose layout changes

Describe how return air path and ceiling plenum use affect room air distribution

Identify the components of a duct system (dampers, access doors, turning vanes, flexible connectors) and their design purpose

Specify duct insulation and seal class requirements for a stated application and explain the energy and condensation consequences

Apply fire- and smoke-damper requirements at rated assemblies and describe the inspection and testing obligations

Explain duct leakage testing procedures and how leakage class affects fan sizing

Perform a basic duct static pressure budget by summing straight-run, fitting, terminal, and filter losses

Read a fan curve and locate the operating point where system resistance intersects it

Diagnose a system with insufficient airflow using static pressure readings and propose corrective action

Describe balancing procedures and the role of balancing dampers and proportional balancing

Explain the role of outdoor air intake location, separation distances, and exhaust re-entrainment risk

Describe economizer operation and the damper and sensor logic that enables free cooling

Trace a typical air-handling unit sequence from mixed-air damper control through filter, coil, fan, and terminal delivery

Identify control failure modes that cause excess outdoor air, coil freeze-up, or simultaneous heating and cooling

Review all prior deliverables and close gaps in duct sizing, pressure budget, and terminal selection

Complete timed practice sets under exam conditions and record error patterns by topic

Re-derive the core equations (continuity, Darcy-Weisbach, fan laws) from memory without notes

Build a one-page reference sheet of key values, unit conversions, and diagnostic checklists