HVAC design for commercial TI: when to reuse VAV boxes, server room cooling, makeup air for coffee bars, and ASHRAE 62.1 mixed-occupancy ventilation.
Manual J vs rule of thumb HVAC sizing: accuracy, time cost, permit acceptance, and the quantifiable costs of oversized systems. Comparison with worked numbers.
Cold-climate heat pump sizing with the three-number method: ASHRAE 99% design temp, Manual J load, and 47/17F capacity. Worked balance-point example.
How to verify refrigerant charge in residential AC systems using superheat and subcooling methods. Complete field procedure with R-410A worked examples, diagnostic matrix, and R-454B transition guidance for technicians.
Learn how to perform a Manual J load calculation for residential HVAC projects. Step-by-step process with common mistakes, ACCA sizing limits, and real-world input tips for contractors.