HVAC Math: Heat Loads, BTU, CFM, Duct Sizing & Refrigeration Basics
Convert BTU/h, tons, kW and °F/°C, calculate conduction and infiltration loads, sum a room-by-room load to size equipment, split 400 CFM per ton over the rooms, size round ducts by velocity, check superheat and subcooling against targets and compare SEER, EER and COP with an operating-cost chart: 8 graded labs for HVAC apprentices and exam practice. Illustrative tables, not copied from Manual J or ASHRAE; your local code and manufacturer data apply; not affiliated with any trade association.
The first lesson is free — no account needed.
About this course
An HVAC math course that works through the heating and cooling of one fictional house, the Lindell house, in a spreadsheet, for HVAC apprentices, students preparing for a trade exam and working technicians. You convert BTU/h into tons and kW and temperatures and temperature differences between °F and °C, calculate conduction heat loss with U × A × ΔT from R-values, turn air changes per hour into CFM for sensible and latent loads, total a room-by-room cooling load and pick the equipment size, split 400 CFM per ton over the rooms and count registers, size round ducts by velocity, check superheat and subcooling against targets, and compare SEER, EER and COP with an operating-cost chart. Illustrative tables, with no affiliation with ACCA, ASHRAE or any trade body. Your local code applies, and the course is no substitute for a licensed technician. The first lab is free.
Lessons
- HVAC Units: BTU/h, Tons, kW and °F/°C (incl. ΔT)Free
- Conduction Heat Loss: U × A × ΔT for Walls, Windows, Doors & Ceiling Pro
- Infiltration & Ventilation Load: CFM × 1.08 × ΔT and the Latent 0.68 Factor Pro
- Room-by-Room Load Summary, BTU per ft² & Equipment Size in Tons Pro
- Airflow: 400 CFM per Ton, Room CFM by Load Share & Register Count (Chart) Pro
- Duct Sizing: Area = CFM ÷ FPM, Round Diameter & Velocity Check Pro
- Superheat & Subcooling: Readings vs Targets for TXV and Piston Systems Pro
- Efficiency & Operating Cost: SEER, EER, COP and Annual Savings (Chart) Pro