HVAC Basics

Mild outdoor temperatures can reduce sensible cooling demand while latent moisture continues. Learn why short AC runtime can leave indoor dew point high.

Furnace heating airflow must keep temperature rise within the rating-plate range while matching blower performance and duct resistance.

A high heat-pump winter bill can reflect weather, auxiliary heat, defrost, thermostat recovery, airflow or faults. Use bills and operating data to find why.

Learn why fixed-orifice and TXV systems respond differently, how manufacturer charging methods use superheat or subcooling, and why absolutes fail.

Draft pressure describes the combustion-air and vent pathway at a defined test point. It must be interpreted with the model, vent, inducer and condensate system.

AC condensate changes with indoor moisture, outdoor dew point, airflow, runtime and drain condition. Learn how to evaluate water removal without a fixed target.

If the furnace blower runs without burner heat, separate FAN ON, post-fault cooling, and a failed ignition sequence before replacing any part.

Learn how to distinguish normal heat-pump frost from persistent ice, what defrost should look like, and when drainage, fan or control problems need service.

Wind, stack effect and pressure differences can pull humid outdoor air through enclosure leaks. Learn how infiltration becomes a measurable moisture load.

Combustion analysis evaluates a furnace using a coordinated set of flue, draft, fuel and airflow measurements. One efficiency percentage is not enough.