HVAC Basics

Outdoor ventilation can add sensible and latent load. Learn how airflow, dew point, humidity ratio, schedule and conditioning determine the moisture demand.

Burners that light and shut off within seconds may indicate flame-proving trouble. Learn what the pattern means and why cleaning is not always the fix.

A heat pump can feel cooler than furnace air or briefly cool during defrost. Learn how fan settings, room trends and backup heat separate normal operation from faults.

Sensible heat ratio compares sensible with total load or capacity. Learn why building SHR and equipment SHR are different and how designers use both.

An auxiliary-heat lockout can reduce unnecessary backup use, but the threshold must preserve required capacity and the approved equipment sequence.

Suction and discharge pressures change with refrigerant type, airflow, load, ambient and controls. Learn what technicians need before confirming charge.

See what a glowing furnace ignitor confirms, why burners may still fail to light, which observations are safe, and which gas tests require a technician.

Undercharge and low airflow can both cause poor cooling or ice. Learn how technicians compare airflow, static pressure, superheat and subcooling safely.

Auxiliary heat starts automatically; Emergency Heat is manually selected for specific failures. Learn what each mode does and when to call for service.

An inducer running with no ignitor glow places the fault before ignition. Learn how draft proving, vents, condensate, and controls affect that step.