HVAC Basics

A blower-off delay can recover sensible cooling but may pass air over a wet coil. Learn how delay length, drainage and controls affect re-evaporation.

If a furnace will not restart after an outage, check thermostat demand and visible power clues safely, preserve fault codes, and avoid repeated breaker resets.

Learn the difference between a heat pump capacity balance point and economic balance point, how each is determined, and why neither is a universal setting.

Return leaks can draw humid attic or crawlspace air; supply leaks can change house pressure. Learn why duct location and pressure determine humidity impact.

Infiltration load is the heat required to warm uncontrolled outdoor air entering through enclosure and duct leaks. Airflow estimation is the critical input.

Learn how high-side pressure becomes condensing saturation temperature and how outdoor airflow, ambient conditions and refrigerant state affect it.

Learn how a clogged condensate drain can stop a high-efficiency furnace, what water clues are safe to inspect, and why vent and pressure checks still matter.

High superheat can reflect low evaporator feeding, undercharge, restriction, high load or measurement error. Learn how technicians separate the causes.

Long heat-pump runtime can be normal in cold weather. Learn how indoor temperature trend, auxiliary heat, airflow and model capacity show when service is needed.

A dirty furnace filter can restrict airflow and open the high limit, but it is not the only cause of short cycling. Learn the safe checks and measurements.