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.

Learn More

Employee working on hvac system

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.

All Case Studies

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.

All Case Studies

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 Studies

Basketball City

Basketball City is a 70,000 sq. ft. “state-of-the-art” Sports & Entertainment facility, Donnelly Mechanical helped identify ongoing issues with their HVAC equipment that included poor performance and premature equipment failure.

All Case Studies

Stay Up to Date with HVAC

Preparing Your HVAC System for Hurricanes and Natural Disasters

HVAC systems are crucial components in maintaining indoor comfort and air quality in both residential and commercial buildings. However, during […]

HVAC Safety: What to Know and Donnelly Mechanical’s Role

For New York City’s commercial buildings, ensuring a comfortable and safe atmosphere for employees and visitors is paramount. At the […]

HVAC in Schools: The Implications of the Potential 88 Degree Ban

As climate change continues to alter weather patterns, heat waves have become more frequent and severe. Schools, as vital institutions […]

Make the Switch

Our contract transition team makes it easy to become a preferred maintenance client.

Learn More