Residential and commercial HVAC share the same basic physics but diverge almost everywhere else. Size and tonnage are the first difference, a typical home runs 2 to 5 tons, while a commercial building can need 10 to 50 tons or more. Location matters too: residential units sit at ground level and in attics or closets, while commercial systems are usually rooftop package units or mechanical-room VRF systems that require crane installs and fall protection.
Commercial systems also tend to be modular and multi-zone, integrating with building automation, economizers, and make-up air. They follow stricter Title 24, fire, and ventilation codes, and they're drained and ducted for higher occupancy loads. Maintenance is scheduled and documented because downtime shuts the business down. Residential service is usually reactive; commercial service is contractual and preventative.
