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.

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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

.77

EMR (Experience Modification Rate)

1989

Over 30 Years of Outstanding Service

200+

Employees

Stay Up to Date with HVAC

Why Demand-Controlled Ventilation Is Becoming the Standard in Commercial HVAC

SUMMARY: Demand-controlled ventilation (DCV) adjusts a building’s airflow in real time based on occupancy or indoor air quality, reducing energy [...]

The Future of Smart Buildings: Digital Twins & Occupant-Centric HVAC Control

SUMMARY: Digital twins are revolutionizing the way smart buildings operate by creating real-time, virtual replicas of physical spaces. When paired [...]

NYC Legionnaires’ Disease Outbreak: What to Know and How to Prevent

NYC is facing a Legionnaires’ disease outbreak, with multiple deaths and illnesses reported as a result. Here’s how to protect yourself and your occupants.

Make the Switch

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

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