HVAC Basics

Size a return filter grille using assigned airflow, usable free area, filter fit, face velocity, connected duct geometry, access and noise evidence.

Trace HVAC filter bypass leakage through rack gaps, wrong dimensions, damaged doors, failed seals and downstream return leaks using visible dust paths.

Follow the technician process for locating pressure taps, documenting operating airflow and interpreting clean or loaded HVAC filter pressure drop.

Compare washable and pleated HVAC filters by tested capture, airflow resistance, fit, cleaning consistency, complete drying needs and equipment approval.

Compare 1-inch and 4-inch HVAC filters by usable media area, airflow resistance, cabinet fit, dust loading, access and actual service conditions.

Understand HVAC filter pressure drop, why airflow and loading change it, and how it differs from total external static pressure at the system blower.

Commission a mini-split by documenting model match, piping, charge, electrical setup, drainage, controls, airflow and measured heating and cooling response.

Verify duct repairs with a commissioning sequence that checks leakage, blower airflow, static pressure and room delivery under documented conditions.

Compare HVAC static pressure with duct leakage testing, including what resistance and tightness measurements prove and why neither can replace the other.

Evaluate mini-split humidity control through sensible and latent load, minimum capacity, fan behavior, infiltration and measured dew point rather than setpoint.