Commercial RTU installation and changeout is a building-integration project performed at the roof boundary. Equipment duty, curb and structure, roofing, ducts, electrical and heating utilities, drainage, economizer, controls, crane logistics, weather, and occupied operations must align. ClimateService coordinates authorized Chicago mechanical scope while design, structural, roofing, electrical, fuel, controls, life-safety, and permitting responsibilities remain assigned.
Define whether the project is a replacement or new RTU point
A like-location changeout, major capacity change, tenant buildout, added zone, relocated unit, or new roof opening creates different design and construction needs. Document served spaces, schedules, occupancy, load, outdoor air, humidity, criticality, future plans, sound, appearance constraints, and acceptable disruption before selecting equipment.
Verify load, airflow, and ventilation basis
Envelope, orientation, people, lighting, equipment, schedules, ventilation, infiltration, distribution, diversity, humidity, and changing tenancy influence required duty. Existing nameplate capacity is one reference, not a complete calculation. Qualified design should establish capacity and outdoor-air requirements without relying on oversizing to cover uncertain data.
Select equipment around real interfaces
Dimensions, operating weight, cooling stages, heat source, fan, external static capability, filters, economizer, relief, orientation, supply and return openings, curb compatibility, sound, low-ambient operation, freeze needs, controls, electrical data, and service clearances affect fit. Manufacturer selection should match the approved basis.
Assess roof, structure, and curb
Support framing, reactions, vibration, curb dimensions, level, corrosion, gasket surface, adapters, roof openings, flashing, insulation, drainage, penetrations, access, fall protection, and maintenance paths require coordinated review. Qualified structural and roofing parties approve their boundaries. An adapter cannot repair an unsound curb or structure.
Survey crane and rooftop logistics
Equipment weight, lifting points, crane reach, street or lot setup, permits where applicable, overhead utilities, roof loading, laydown, public separation, weather, wind limits, rigging path, adjacent units, air intakes, and emergency access affect the lift. Qualified rigging parties control lift planning and execution.
Coordinate ducts and the weather boundary
Supply and return separation, adapters, transitions, leakage, insulation, flexible connections, external static, fire or smoke interfaces, curb gasket, roof flashing, temporary openings, and protection from rain and debris influence long-term performance. Existing distribution should be evaluated rather than hidden beneath the new cabinet.
Map electrical, heating, and drainage connections
Voltage, phase, capacity, disconnect, overcurrent protection, grounding, controls wiring, gas or hydronic service, venting, condensate pan, trap, line, heat trace, roof drainage, and service receptacles need assigned trade boundaries. Existing utility capacity and condition should be verified before crane day.
Integrate economizer and controls
Outdoor-air hood, dampers, sensors, minimum position, relief, fan command, cooling and heating stages, safeties, alarms, schedules, thermostats, BAS points, smoke or life-safety interfaces, overrides, and restart behavior should follow an approved sequence. Factory configuration still requires field setup and functional testing.
Plan shutdown and temporary conditioning
Weather, occupancy, tenant or process consequence, isolation, demolition, roof opening, delivery, crane, trades, utility work, controls availability, startup, and contingency determine the outage. Temporary conditioning needs verified capacity, power, distribution, drainage, monitoring, security, and removal criteria rather than a generic rental assumption.
Control removal and rooftop protection
Electrical and fuel isolation, refrigerant recovery, oils, filters, residual water, component weight, open ducts, curb exposure, debris, roofing membrane, demolition path, salvage, disposal, and neighboring equipment require assigned procedures. Photographs and protected openings preserve existing conditions while the old RTU is removed.
Install and commission the connected system
Checks may include placement, anchorage, gasket, adapters, panels, ducts, filters, fan rotation, airflow, current, cooling and heating stages, refrigerant response, safeties, drainage, economizer, outdoor air, relief, controls, alarms, schedules, cycling, and representative zones. Weather-limited modes should receive deferred tests.
Balance distribution after the RTU is stable
Unit airflow, external static, fan settings, filter and coil pressure drop, supply branches, dampers, terminals, return paths, doors, zone sensors, and occupancy influence delivered comfort. Qualified balancing may be separate, yet its results should inform final fan and control settings. Correct rooftop temperatures do not prove that every perimeter or high-load zone receives the intended air.
Prepare operators for normal and abnormal conditions
Facility staff should know RTU identity, served zones, schedule, fan behavior, cooling and heating stages, economizer operation, alarm route, filter sizes, drain observations, roof access, and emergency shutdown contact. Training should use the installed controller and actual roof path. Overrides or seasonal adjustments should follow an authorized record rather than informal memory.
Close deferred seasonal acceptance
Weather may prevent full cooling, heating, low-ambient, defrost, economizer, or maximum-load proof. The closeout should list each unavailable mode, required conditions, measurements, representative zones, responsible company, target window, and corrective path. This keeps honest limitations from becoming forgotten gaps after project invoices are closed.
ClimateService delivers a maintainable rooftop baseline
ClimateService documents equipment, roof and curb interfaces within scope, settings, photographs, startup readings, tested modes, unavailable conditions, open distribution or trade items, warranties, filters, maintenance access, and seasonal follow-up. Facility teams receive operational continuity instead of losing project knowledge once crane, roofing, and installation crews leave.
