Understanding Packaged Rooftop HVAC Units: Key Components & Configurations

Technical Resource

A packaged rooftop unit (RTU) houses the major components of a commercial HVAC system — compressor, condenser coil, evaporator coil, blower, and controls — in a single weatherproof cabinet mounted on the roof, rather than splitting them between indoor and outdoor sections.

Common configurations include straight air conditioning (cooling only), heat pump (electric heating and cooling), and gas/electric units that pair a gas furnace section with electric cooling — the right configuration depends on the building's heating needs, utility availability, and local code.

Because all major components sit in one cabinet, RTUs are generally easier to service and replace than fully split systems, and ductwork typically connects directly through the roof curb into the building below.

Sizing and configuration should be based on a proper load calculation for the space, not just the tonnage of the unit being replaced — undersized or oversized equipment can lead to poor comfort, higher operating cost, and shorter equipment life.

Routine maintenance items specific to RTUs include coil cleaning, condensate drain checks, belt and filter changes, and curb/flashing inspections, since these units are directly exposed to weather year-round.