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Commercial Rooftop Unit Installation & Replacement Across the NYC Metro
When a packaged rooftop unit reaches the end of its service life, the changeout has to land on schedule, on curb, and with minimal disruption to tenants below. Com+ Mechanical engineers, rigs, and commissions RTU replacements for office, retail, and mixed-use properties across the five boroughs and surrounding metro. From single gas-pack swaps to multi-unit rooftop fleets, we handle the crane lift, the curb adapter, the electrical and gas tie-ins, and the controls integration end to end.
Signs Your Rooftop Unit Is Due for Replacement
Repeated compressor failures or low refrigerant charge
A unit that keeps losing a compressor or needs annual recharges is usually past economical repair. On older R-22 rooftops the refrigerant is phased out and costly, making a high-efficiency R-410A or R-454B replacement the sounder long-term investment than another teardown.
Cracked heat exchanger in the gas section
A cracked or corroded heat exchanger in a gas/electric package poses a carbon monoxide risk and typically condemns the heating side of the unit. When the exchanger fails on a 15-to-20-year-old RTU, full replacement is generally the safer and more cost-effective path than swapping the exchanger alone.
Rusted-through cabinet, base rails, or curb corrosion
Standing water and a deteriorated drain pan rot the unit base and the roof curb. Once the cabinet sheet metal and base rails corrode through, the unit can no longer be reliably sealed or supported, and a changeout with a fresh curb adapter is required.
Rising energy bills and inability to hold setpoint
Aging single-stage compressors and fouled coils force the unit to run longer to maintain space temperature, driving up consumption. A modern two-stage or variable-capacity rooftop with a functioning economizer can cut runtime significantly and helps the building's carbon profile under Local Law 97.
Failed economizer and stuck outdoor-air dampers
Seized economizer actuators and broken damper linkages leave the unit pulling minimum or excessive outside air, wrecking both efficiency and ventilation compliance. On end-of-life units the controls and damper assemblies are often obsolete and unsupported, favoring replacement.
Obsolete unit with no parts availability
When a rooftop unit's compressors, boards, or blower assemblies are no longer manufactured, every breakdown means longer downtime and improvised fixes. At that point a planned replacement on your schedule beats an emergency failure during peak cooling or heating season.
Packaged Rooftop Unit Replacement, Engineered for Occupied Buildings
A commercial RTU replacement is far more than lifting one box off and setting another down. The new unit rarely matches the old footprint, so the curb, the supply and return duct openings, the gas train, the disconnect, and the economizer all have to be reconciled before the crane ever shows up. Com+ Mechanical specializes in packaged rooftop unit installation and changeout for commercial properties throughout NYC and the metro area — gas/electric and electric/electric packaged units, heat-pump rooftops, and high-efficiency models specified to help buildings stay ahead of Local Law 97 emissions thresholds. We start with a load assessment and a field survey of curb dimensions, structural capacity, rigging path, and existing controls, then deliver a turnkey scope: demolition and disposal of the old unit, curb adapter fabrication, crane rigging, setting, gas and electrical tie-ins, economizer and sensor setup, refrigerant charge verification, and full startup and commissioning. The result is a unit that fits the opening, talks to your building automation system, and runs at its rated capacity from day one.
What a Com+ RTU Installation Includes
Why Replace Your RTU With Com+ Mechanical
Our Simple Process
From call to comfort in 4 easy steps
Assessment & Load Verification
We survey the existing unit, curb, and roof access, verify cooling and heating loads for the space, and confirm structural capacity and rigging path. You receive a defined scope and equipment selection sized to the building, not just a like-for-like swap.
Engineering & Scheduling
We fabricate the curb adapter, order the unit and any required disconnect or gas-train components, and coordinate the crane, street occupancy permits, and roof protection. The lift is scheduled around tenant hours to limit disruption.
Changeout & Tie-In
The old unit is recovered, disconnected, and rigged off; the curb adapter is set and sealed; and the new RTU is craned into place. We complete gas, electrical, condensate, and duct transitions and pressure-test the connections.
Commissioning & Handover
We verify refrigerant charge, set the economizer, balance airflow to design CFM, integrate controls with the BAS, and run the unit through heating and cooling modes. You get a documented startup and a walkthrough before we leave the roof.
Types of Systems We Install
Gas/Electric Packaged Rooftop Units
The most common configuration on NYC commercial roofs — gas-fired heating with electric cooling in a single packaged cabinet, serving offices, retail, and mixed-use spaces.
- •Self-contained gas heat exchanger and burner section
- •Single- or two-stage cooling with integrated condenser
- •Economizer-ready for free cooling and ventilation
- •Requires gas train tie-in and combustion safety checks at startup
Electric/Electric & Heat-Pump Rooftop Units
All-electric packaged units, including heat-pump rooftops that provide both heating and cooling — increasingly specified for electrification and Local Law 97 emissions goals.
- •No gas connection or combustion venting required
- •Heat-pump models deliver heating and cooling from one system
- •Strong fit for buildings electrifying to cut carbon intensity
- •May require electrical service or disconnect upsizing
High-Efficiency & Variable-Capacity Rooftops
Premium packaged units with two-stage or variable-speed compressors and ECM blowers that modulate to load, reducing runtime and energy use versus legacy single-stage equipment.
- •Variable or staged capacity matches output to demand
- •ECM/variable-speed supply fans for lower fan energy
- •Advanced onboard controls and BAS connectivity
- •Higher IEER/SEER2 ratings for operating-cost and compliance gains
Why NYC Property Teams Choose Com+ Mechanical
Commercial Rooftop Specialists
We focus on packaged rooftop systems for office, retail, and mixed-use buildings — curbs, adapters, rigging, and controls — not residential split systems. Your changeout is handled by a team that does this work daily.
Built for Occupied Buildings
Crane lifts, gas tie-ins, and tenant-facing downtime are planned around your operating hours and building rules. We coordinate with property management, security, and other trades to keep the building running.
24/7 Metro-Wide Response
Across the five boroughs, Nassau, Westchester, northern NJ, and Stamford, we respond to rooftop emergencies and keep replacement projects moving..
Efficiency & Compliance Minded
We specify rooftop equipment with an eye to Local Law 97 emissions thresholds and operating cost, helping owners replace aging, inefficient units with systems that reduce both runtime and carbon exposure.
Transparent Pricing
No fees. No surprises. Just honest service.
Rooftop Assessment & Replacement Proposal
A field survey of the existing RTU, curb, roof access, and load, delivered as a defined replacement scope and equipment recommendation.
- On-site survey of unit, curb dimensions, and rigging path
- Cooling/heating load and structural capacity review
- Equipment selection and efficiency options
- Itemized written replacement proposal
RTU Replacement & Installation
Turnkey changeout: demolition and disposal, curb adapter, crane set, gas and electrical tie-ins, controls integration, and commissioning.
- Old unit recovery, disconnect, and disposal
- Custom curb adapter fabrication and sealing
- Crane rigging, setting, and permit coordination
- Gas/electrical tie-in, charge verification, and BAS integration
- Full startup, airflow balancing, and commissioning
Rooftop Maintenance Agreement
Scheduled preventive maintenance on new and existing rooftop units to protect the investment, hold efficiency, and extend service life.
- Seasonal cooling and heating inspections
- Coil cleaning, belt, and economizer service
- Filter changes and condensate/drain pan service
- Priority scheduling for agreement clients
- Documented unit condition reporting
All pricing is scoped after an on-site assessment, because crane access, curb adaptation, gas and electrical conditions, and controls integration vary by building and drive the real cost. Pricing is presented as a fixed written proposal before any work begins..
Own a Commercial Property?
Business+ plans start at $499/year — includes 2 rtu tune-ups, 10% off all services, and priority scheduling.
Equipment & Brands We Service
Factory-trained technicians for all major HVAC manufacturers
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Frequently Asked Questions
Get answers to common questions about our services
Will you need to replace the roof curb, or can the new unit reuse the existing one?
In most replacements the original curb stays and we fabricate a custom curb adapter so the new unit's supply and return openings line up with the existing duct penetrations. This avoids opening the roof. If the existing curb is corroded through or structurally compromised, we'll flag it during the assessment and include curb work in the scope.
How long does a rooftop unit changeout take, and how much downtime should tenants expect?
A single-unit changeout is frequently a one-day crane operation, with tie-ins and commissioning completed the same day or the following morning depending on electrical and gas conditions. We schedule the lift around tenant hours wherever possible so conditioned-air downtime to the space below is kept short. Larger or multi-unit projects are phased to keep occupied areas served.
Can you replace multiple rooftop units across a portfolio of buildings?
Yes. We regularly handle multi-unit and multi-site rooftop replacement programs for property managers and owners with portfolios across the NYC metro, standardizing equipment and phasing the lifts so each building stays operational. We can plan a staged capital replacement schedule rather than waiting for units to fail one by one.
Do you offer emergency response if a rooftop unit fails completely?
Yes. We provide 24/7 response across the five boroughs, Nassau, Westchester, northern NJ, and Stamford for rooftop failures, and can move quickly on an emergency replacement or temporary measures when a unit is down during peak season..
How does a new RTU help with Local Law 97 and energy costs?
Older rooftop units run on single-stage compressors and degraded coils that consume far more energy than today's two-stage and variable-capacity equipment. Replacing an aging unit with a high-efficiency or heat-pump rooftop lowers electricity and gas use and reduces the building's carbon intensity, which directly affects Local Law 97 emissions calculations. We can specify equipment with that compliance goal in mind.
Will the new unit integrate with our existing building automation system?
Yes. As part of commissioning we map the new unit's control points to your BAS or existing thermostats so it sequences, reports status, and alarms the way your facilities team expects. For multi-building portfolios we coordinate so the rooftop equipment reports consistently across sites..
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Planning a Rooftop Unit Replacement? Let's Scope It Right.
Whether you're replacing one failed gas pack or planning a phased rooftop changeout across a portfolio, Com+ Mechanical delivers the assessment, the curb adapter, the crane set, and the commissioning under one accountable contractor. Get a written, fixed-scope proposal built around your building, your tenants, and your schedule.
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