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
.58
EMR (Experience Modification Rate)
1989
Over 30 Years of Outstanding Service
200+
Employees
NYC UVGI System
Donnelly Mechanical worked to provide a safe working environment for industry employees by installing a duct-mounted UVGI system on each office floor.
All Case Studies
Loro Piana
With a fast-paced timeline, Donnelly replaced Loro Piana’s existing heat pump VRF system with an updated higher efficiency heat recovery VRF system.
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Long Island Healthcare Facility
With a brand new laboratory facility being constructed, new mechanical equipment was required. This included everything from new chillers, boilers, fan coil units, & custom AHUs.
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Boston Properties
The base building’s existing steam absorption chillers, which provide the large tonnage central air conditioning, had served beyond its useful life and needed to be replaced.
All Case StudiesStay Up to Date with HVAC
Heat recovery systems are transforming commercial HVAC by capturing and reusing waste heat to boost energy efficiency, reduce costs, and support sustainability goals.
As smart HVAC systems become more connected, they also become prime targets for cyberattacks that can disrupt operations, compromise data, and create serious security risks. This blog outlines common cyber threats—like ransomware, unauthorized access, and phishing—and offers best practices such as network segmentation, encryption, and regular system updates to strengthen HVAC cybersecurity.
Retrofitting HVAC systems is essential for enhancing energy efficiency, ensuring regulatory compliance, and improving overall building performance, especially in legacy systems.
Make the Switch
Our contract transition team makes it easy to become a preferred maintenance client.
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