RTU Repair & Diagnostics
Fast, accurate diagnostics and repairs for all major commercial rooftop unit brands. Our certified technicians restore system performance quickly, minimizing downtime for your Long Island facility.
Long Island's commercial buildings demand dependable rooftop unit performance year-round—from humid summers to harsh winters. Denair HVAC delivers expert RTU service, repair, preventive maintenance, and emergency response backed by 19+ years of experience, manufacturer-certified technicians, and a commitment to minimizing your downtime and operational disruptions.
Comprehensive RTU solutions for Long Island commercial facilities—from routine maintenance to full system installation and emergency repairs.
Fast, accurate diagnostics and repairs for all major commercial rooftop unit brands. Our certified technicians restore system performance quickly, minimizing downtime for your Long Island facility.
Proactive maintenance plans that extend rooftop unit lifespan, reduce energy costs, and prevent costly breakdowns. Free preventive maintenance included for up to 18 months on all new RTU installations.
Turnkey commercial rooftop unit installation with full project management, value engineering, and end-to-end coordination—saving clients up to 35% on HVAC budgets.
Round-the-clock emergency RTU service with same-day response—usually within 4 hours. Technicians arrive fully equipped to handle urgent repairs on all major rooftop unit brands.
Modernize aging rooftop HVAC equipment with targeted retrofits and expert system tuning to optimize performance, energy efficiency, and compliance—without full system replacement.
Smart controls and automation solutions integrated with your rooftop units to significantly reduce energy costs and environmental impact across your commercial property.
Our certified technician visits your Long Island facility to conduct a thorough inspection of your rooftop unit, evaluating system condition, performance history, and any immediate concerns to develop an accurate scope of work.
See how Denair HVAC has kept commercial facilities running efficiently across Long Island and the greater New York area.
"I didn't even know about their referral program sending DENAIR to one of my commercial tenants. It was a nice surprise to get paid for referral. Based on the tenant's feedback, the job was well-done. Now it's no brainer to recommend DENAIR to all my tenants"
"I know DENAIR for years dealing with their commercial insurance matters. I know they provide best in class services and have recommended them to a couple of major construction industry players. I can definitely say – the bigger the project the bigger my commission is"
"Impeccable install. You can tell they're pros the moment they walk in."
"Denair is professional and courteous."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"What a great service. I randomly called to get multiple system inspected in my building. They came on time, done a great job and provided a detailed report. I love their transparency."
"Great company, our office was getting hotter by the minute. Denair had a tech on site with in the hour and the ac working perfect in two hours"
"Dennis was always available when I called on him. Never was any additional work generated on any quote/contract awarded. Reliable, expert and a pleasure to work with. A real value!"
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"I recently used Denair for some repairs to my small two-story office building, and I have to say they are the most honest, hard-working and value focused HVAC provider I have ever experienced! Not only was the price competitive, but more importantly they helped reduce my energy costs from an..."
"They have the best Engineering Service I have ever seen; they are always available on request and perform the maintenance in the most efficient way. Great Service."
"Crew was respectful, fast, and left our place spotless. Five stars."
"excellent work and quality"
"Denair is the most dependable HVAC service company in New York!"
"I didn't even know about their referral program sending DENAIR to one of my commercial tenants. It was a nice surprise to get paid for referral. Based on the tenant's feedback, the job was well-done. Now it's no brainer to recommend DENAIR to all my tenants"
"I know DENAIR for years dealing with their commercial insurance matters. I know they provide best in class services and have recommended them to a couple of major construction industry players. I can definitely say – the bigger the project the bigger my commission is"
"Impeccable install. You can tell they're pros the moment they walk in."
"Denair is professional and courteous."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"What a great service. I randomly called to get multiple system inspected in my building. They came on time, done a great job and provided a detailed report. I love their transparency."
"Great company, our office was getting hotter by the minute. Denair had a tech on site with in the hour and the ac working perfect in two hours"
"Dennis was always available when I called on him. Never was any additional work generated on any quote/contract awarded. Reliable, expert and a pleasure to work with. A real value!"
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"I recently used Denair for some repairs to my small two-story office building, and I have to say they are the most honest, hard-working and value focused HVAC provider I have ever experienced! Not only was the price competitive, but more importantly they helped reduce my energy costs from an..."
"They have the best Engineering Service I have ever seen; they are always available on request and perform the maintenance in the most efficient way. Great Service."
"Crew was respectful, fast, and left our place spotless. Five stars."
"excellent work and quality"
"Denair is the most dependable HVAC service company in New York!"
"I didn't even know about their referral program sending DENAIR to one of my commercial tenants. It was a nice surprise to get paid for referral. Based on the tenant's feedback, the job was well-done. Now it's no brainer to recommend DENAIR to all my tenants"
"I know DENAIR for years dealing with their commercial insurance matters. I know they provide best in class services and have recommended them to a couple of major construction industry players. I can definitely say – the bigger the project the bigger my commission is"
"Impeccable install. You can tell they're pros the moment they walk in."
"Denair is professional and courteous."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"What a great service. I randomly called to get multiple system inspected in my building. They came on time, done a great job and provided a detailed report. I love their transparency."
"Great company, our office was getting hotter by the minute. Denair had a tech on site with in the hour and the ac working perfect in two hours"
"Dennis was always available when I called on him. Never was any additional work generated on any quote/contract awarded. Reliable, expert and a pleasure to work with. A real value!"
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"I recently used Denair for some repairs to my small two-story office building, and I have to say they are the most honest, hard-working and value focused HVAC provider I have ever experienced! Not only was the price competitive, but more importantly they helped reduce my energy costs from an..."
"They have the best Engineering Service I have ever seen; they are always available on request and perform the maintenance in the most efficient way. Great Service."
"Crew was respectful, fast, and left our place spotless. Five stars."
"excellent work and quality"
"Denair is the most dependable HVAC service company in New York!"
Long Island businesses trust Denair HVAC for commercial rooftop unit service because of our unmatched technical depth, transparent pricing, and guaranteed results.
Technicians trained and certified by major RTU manufacturers, ensuring expert service on any brand across Long Island commercial properties.
24/7 emergency RTU service with arrival typically within 4 hours—because Long Island businesses can't afford extended downtime.
All unintended costs are covered at our expense. No surprise invoices—just transparent, value-engineered pricing that consistently beats the competition.
Founded in 2007 and recognized by Inc. 5000, Denair HVAC brings nearly two decades of commercial HVAC expertise to every Long Island project.
Dedicated specialists delivering expert commercial RTU service across Long Island.
Founder & CEO
Dennis founded Denair HVAC in March 2007 with one man and a beat-up used truck right after being laid off from a 7-year career in the HVAC industry. Armed with over 17 years of hands-on HVAC expertise and deep knowledge of Brooklyn and NYC's commercial building landscape, he grew the company to $2 million in revenue within just five years. Under his strategic leadership, Denair earned recognition by Inc. 5000 as one of America's fastest-growing companies. Dennis oversees all aspects of the business—from rooftop unit replacement projects across Brooklyn's flat-roof commercial buildings to large-scale capital improvement contracts throughout the NYC metro area—ensuring every client receives honest, high-quality service.
Financial Manager
Tanya brings over 15 years of experience in finance, budgeting, and forecasting to the Denair HVAC team. She manages all aspects of accounting, financial planning, and insurance for the company—ensuring every rooftop unit replacement and installation project is backed by financial integrity and transparent cost management. Her meticulous approach to budgeting directly supports Denair's ability to offer fixed proposal pricing and value-engineered solutions that consistently save Brooklyn and NYC clients thousands of dollars. Tanya's financial stewardship has been a cornerstone of Denair's steady growth from a one-man operation to a recognized industry leader.
Lead Estimator
Farrukh has been with Denair HVAC since 2010, making him one of the company's longest-serving and most trusted team members. As Lead Estimator, he is responsible for preparing comprehensive and timely bid proposals for rooftop unit replacement and installation projects across Brooklyn and the wider NYC metro area. His expertise in tracking opportunities with vendors, subcontractors, and customers ensures every scope is accurately priced—with alternates and revisions provided for each bid. Farrukh's value engineering approach has helped Brooklyn property managers and business owners save significantly on their HVAC capital improvement budgets.
Service Manager
Thomas leads Denair HVAC's service operations, overseeing fast response times, efficient technician scheduling, and consistent service quality for rooftop unit projects throughout Brooklyn. He coordinates field technicians and customer communications to keep RTU systems running reliably—minimizing downtime for commercial tenants, property managers, and building operators. Thomas ensures that Denair's commitment to same-day service (usually within 4 hours for emergencies) is consistently met, and that every rooftop unit installation or repair is delivered with the smooth, professional experience Brooklyn clients expect from an Inc. 5000-recognized contractor.
Application Engineer
Ramil designs and supports HVAC systems tailored to the specific performance and efficiency needs of each Brooklyn building. Specializing in rooftop unit applications, he oversees equipment selection, technical planning, and engineering support to ensure every RTU installation delivers long-lasting reliability, meaningful energy savings, and full compliance with NYC building codes and LL97 sustainability mandates. Ramil's engineering expertise is particularly valuable for Brooklyn's dense stock of flat-roof commercial and mixed-use buildings, where precise load calculations and rooftop structural considerations are critical to a successful RTU replacement or new installation.
VP Business Development
Anastasiya leads Denair HVAC's business development and new client acquisition strategy, with a focus on building long-term partnerships with property management firms, general contractors, and building owners across Manhattan and the greater NYC metro area. In her role, she identifies market opportunities, develops strategic partnerships, and implements growth initiatives that have helped Denair expand its footprint across some of New York's most recognized property management companies—including AKAM, Douglas Elliman, Related, and Rose Associates. Anastasiya's client-first approach ensures that every new relationship is built on transparency, reliability, and measurable value.
Marketing Manager
Natalja oversees Denair HVAC's brand presence and client relationships, ensuring that building owners, property managers, and facility operators across Manhattan can easily discover and connect with the HVAC expertise they need. As Marketing Manager, she develops and executes strategies that communicate Denair's unique value—from 24/7 emergency availability to Inc. 5000 recognition—to the right audiences across New York City's competitive commercial real estate and residential markets. Her work building public relations and strategic outreach has played a significant role in Denair's growth and continued reputation as one of NYC's most trusted HVAC contractors.
Commercial HVAC service call costs typically range from $150 to $500 depending on the complexity of the system, travel distance, and time of service. For rooftop units, diagnostic calls may run higher due to the equipment size and access requirements. Denair HVAC provides free estimates and transparent, fixed-price proposals so you always know the cost before any work begins.
Speak with a certified RTU specialist for a free consultation and honest answers.
Denair HVAC provides commercial rooftop unit service across Long Island and the greater New York Metro Area, including all five boroughs and surrounding counties.
11+ Regions
Service Area
24/7 Service
Emergency Availability
Within 4 Hours
Response Time
Contact us to confirm coverage and schedule your commercial RTU service today.
Recognized as one of America's fastest-growing companies
Full OSHA safety compliance on every rooftop job site
Licensed mechanical contractor serving New York commercial clients
Fill out the form below and a Denair HVAC specialist will respond promptly with a free estimate and tailored recommendations for your commercial rooftop unit needs.
For immediate assistance, feel free to give us a direct call at 718-791-5074.
For immediate assistance, feel free to give us a direct call at 718-791-5074.