Set a Packaged Rooftop Unit (RTU)

Use the manufacturer's designated lifting holes/lugs and a spreader bar so the slings pull vertically and don't crush the cabinet or coils. Confirm the rigging is rated for the actual unit weight (check the nameplate, not a guess) and that the crane has capacity at the working radius.

⚠ Do not lift over occupied areas. Keep all hands clear of the load; only the signal person directs the crane.

Run tag lines so ground/roof crew can steady and orient the unit during the pick and landing without anyone reaching under the load. Bring it over the curb slowly and orient supply/return correctly before lowering.

Tools: Tag lines

⚠ Never get under a suspended load. Wind gusts can swing the unit — abort the pick if wind exceeds the rigging plan limit.

Before landing, verify the curb is level (an out-of-level curb makes the unit's condensate drain pan hold water and the doors/panels not seal). Lay a continuous curb gasket on the curb top so it seals the supply and return openings as the unit lands.

⚠ A water-holding pan from an out-of-level set leads to overflow and roof leaks.

Lower slowly and let the unit's base settle squarely onto the gasketed curb so the supply/return openings line up with the curb openings and the gasket compresses evenly all the way around. Confirm no gaps where return air could short-circuit or rain could enter.

Once seated, weatherproof every roof penetration and the unit/curb joint — counter-flashing, sealant at fasteners, and any factory storm collars — so wind-driven rain cannot get under the unit or into the duct openings.

Land the supply and return ductwork to the curb collars, sealing the connections with mastic/UL181 so there's no leakage into the unconditioned roof space. Keep transitions smooth to protect the design CFM.

Tools: Duct sealant/mastic, UL181 foil tape

Provide a code-required disconnecting means within sight of the unit on the roof and feed the unit through a liquid-tight whip. Verify supply voltage and that wire/breaker (MCA/MOCP) match the nameplate; bond/ground properly.

⚠ Verify the circuit is de-energized and locked out before landing conductors.

Run gas to the unit with a manual shutoff and sediment/drip leg at the unit ahead of the gas valve, then leak-check every joint electronically or with bubbles. Never check for gas leaks with a flame.

Tools: Electronic gas leak detector

⚠ Never use a flame to find a gas leak.

Install a properly-sized condensate trap (the RTU draw-through coil needs a deep enough trap to overcome the negative pressure) and route the drain to a legal point — not just dumping onto the roof membrane where it can pond or freeze.

Mount the factory economizer or fresh-air/return-air hood and bird screen, set the minimum-position and changeover (dry-bulb or enthalpy) per the spec, and confirm the dampers stroke fully and seal when commanded closed.

On a 3-phase unit, verify phase rotation with a rotation meter so the scroll compressor and blower turn the correct way. A scroll run backward is noisy, doesn't pump, and will fail — swap any two line leads at the disconnect to correct rotation.

Tools: Phase-rotation meter

⚠ A scroll compressor run backwards even briefly can overheat — correct rotation before extended operation.

Run heat and cool: set/verify manifold pressure and a CO/combustion check on gas heat, confirm temperature rise/split in range, check compressor amps vs RLA and refrigerant operating readings, and confirm the economizer and safeties function.

Tools: Manometer, Combustion analyzer, Clamp meter