We Provide Solutions.
We are New York City’s premier provider of innovative commercial HVAC service, maintenance and construction. With over 30 years’ experience and 200+ employees, we serve NYC’s most prominent commercial organizations by providing innovative HVAC solutions to ensure comfort, maximum efficiency, improved indoor air quality and system reliability.
Services & Solutions
We Keep Customers Comfortable with Reliable AC Repair, Maintenance, & Installation!
Preventive Maintenance
Donnelly Mechanical provides custom HVAC preventive maintenance services for a distinguished clientele within many of New York City’s prestigious buildings.
Commercial HVAC Service
Our unique NYC zoning system allows our factory trained technicians to respond quickly either by van or on foot in the event there is a service-related emergency.
Replacements & Upgrades
Our technical team goes beyond the general maintenance and repair services scope. Our turn-key client direct projects range from equipment replacements to design build solutions to high efficiency system upgrades.
New Commercial Construction
From initial survey to project completion, Donnelly effectively manages even the most complex HVAC construction projects with professionalism and ease.
Indoor Air Quality Solutions
Clean indoor air is an office amenity that matters to employees. Our experts test, monitor, improve and sustain Indoor Air Quality to ensure wellbeing and productivity for you, your employees and customers
1,700
Distinguished Maintenance Clients throughout NYC
.77
EMR (Experience Modification Rate)
1989
Over 30 Years of Outstanding Service
200+
Employees
Stay Up to Date with HVAC
SUMMARY: As New York City moves toward 2026, building owners are prioritizing HVAC efficiency upgrades to meet Local Law 97 [...]
Get ahead of NYC’s unpredictable winter 2025 with proactive HVAC maintenance to boost efficiency, reliability, and peace of mind all season long.
SUMMARY: Demand-controlled ventilation (DCV) adjusts a building’s airflow in real time based on occupancy or indoor air quality, reducing energy [...]
Make the Switch
Our contract transition team makes it easy to become a preferred maintenance client.
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