Clean air is an office amenity that matters to employees
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
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SUMMARY New York City is increasing cooling tower oversight in 2026 to reduce Legionella risk and protect public health. This [...]
SUMMARY Indoor air quality expectations are rising in New York City, and poor ventilation is increasingly treated as a tenant [...]
Make the Switch
Our contract transition team makes it easy to become a preferred maintenance client.
Get in Touch