AC Tonnage by Room Size: Sizing Chart and How to Calculate It
How to size AC tonnage by room or house square footage. A square-footage-to-tonnage chart, the 20 BTU per sq ft rule, climate adjustments, and why room-by-room sizing beats rules of thumb.
Fan Laws Explained: How Blower Speed Affects Airflow
The three fan affinity laws relate blower speed to airflow, static pressure, and power. Why a 10% speed increase costs 33% more power, with worked examples.
What Is CFM and How to Calculate It
CFM is the volume of air your HVAC system moves per minute. What it means, the 400 CFM per ton rule, the formula to size airflow per room, and how to measure it.
Refrigerant Overcharge vs Undercharge: How to Tell
How to tell if an AC is overcharged or undercharged using superheat and subcooling, the symptoms of each, and why airflow must be verified before touching the charge.
How Many BTU Do I Need? AC Sizing for Every Room and Home
The right BTU for any room or home — the 20 BTU rule, adjustments for climate, ceiling height, sun, and insulation. Includes a quick-reference size table and worked examples.