RTU Diagnostics & Repair
Expert diagnosis and repair of Lennox rooftop units for Manhattan commercial properties. Our certified technicians identify faults fast and restore full operation, typically within 4 hours of your call.
Manhattan's commercial buildings demand reliable climate control year-round — from sweltering midtown summers to frigid January nights. Denair HVAC's certified technicians specialize in Lennox rooftop unit diagnostics, repair, and maintenance, delivering same-day service within 4 hours. Keep your RTU running at peak efficiency and avoid costly downtime with New York's trusted HVAC experts.
Comprehensive Lennox RTU repair, maintenance, and upgrade solutions for Manhattan commercial and residential buildings.
Expert diagnosis and repair of Lennox rooftop units for Manhattan commercial properties. Our certified technicians identify faults fast and restore full operation, typically within 4 hours of your call.
Around-the-clock emergency response for Lennox RTU failures. Technicians arrive fully equipped to handle urgent breakdowns on all Lennox models, minimizing operational disruption in any season.
Proactive Lennox RTU maintenance plans that maximize efficiency, extend equipment lifespan, and reduce energy costs. Includes customized annual contracts and a client loyalty program.
Targeted retrofits and tune-ups to modernize aging Lennox rooftop equipment. Optimize performance, meet current NYC energy standards, and extend system life without costly full replacement.
Smart controls and automation solutions for Lennox RTU systems that significantly reduce energy costs and environmental impact across Manhattan commercial buildings.
Post-repair air testing and balancing with certified reports to ensure Lennox rooftop systems deliver peak performance and comply with NYC building codes after any service or installation.
Call or contact us and our team will schedule a technician visit, typically the same day. For Manhattan emergency RTU failures, we aim to dispatch within 4 hours — because in a city that never stops, neither do we.
See how Denair HVAC has restored comfort and efficiency for commercial clients across Manhattan and NYC.
"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"
"Denair is the most dependable HVAC service company in New York!"
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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..."
"Great reliable HVAC company, a very rare thing to say these days — the pricing is very competitive and the work is reliable. The staff is professional and courteous, they clean up after themselves and always answer. I would recommend them!"
"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."
"Impeccable install. You can tell they're pros the moment they walk in."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"Crew was respectful, fast, and left our place spotless. Five stars."
"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."
"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!"
"Amazing HVAC vendor who is doing multiple accounts for my company."
"excellent work and quality"
"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"
"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"
"Denair is the most dependable HVAC service company in New York!"
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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..."
"Great reliable HVAC company, a very rare thing to say these days — the pricing is very competitive and the work is reliable. The staff is professional and courteous, they clean up after themselves and always answer. I would recommend them!"
"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."
"Impeccable install. You can tell they're pros the moment they walk in."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"Crew was respectful, fast, and left our place spotless. Five stars."
"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."
"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!"
"Amazing HVAC vendor who is doing multiple accounts for my company."
"excellent work and quality"
"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"
"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"
"Denair is the most dependable HVAC service company in New York!"
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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..."
"Great reliable HVAC company, a very rare thing to say these days — the pricing is very competitive and the work is reliable. The staff is professional and courteous, they clean up after themselves and always answer. I would recommend them!"
"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."
"Impeccable install. You can tell they're pros the moment they walk in."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"Crew was respectful, fast, and left our place spotless. Five stars."
"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."
"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!"
"Amazing HVAC vendor who is doing multiple accounts for my company."
"excellent work and quality"
"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"
Denair HVAC brings over 19 years of certified expertise to every Lennox rooftop unit repair in Manhattan — backed by guarantees you can count on.
Technicians are trained and certified by Lennox, ensuring every Manhattan RTU repair meets manufacturer standards.
We dispatch within 4 hours for urgent Lennox RTU calls across Manhattan and all NYC boroughs.
All unintended repair costs are covered at our expense — no surprise invoices on your Manhattan rooftop job.
Since 2007, Denair has served NYC commercial buildings with honest, code-compliant HVAC repair solutions.
Experienced professionals dedicated to keeping Manhattan buildings comfortable.
Founder & CEO
Dennis founded Denair HVAC in March 2007 with a single used truck and a vision to deliver honest, affordable HVAC service to New York. With over 17 years of hands-on experience across every aspect of the HVAC industry — from rooftop unit diagnostics to full-scale commercial installations — Dennis built the company from the ground up, growing it to over $2 million in revenue within five years. His leadership has guided Denair to recognition by Inc. 5000 as one of America's fastest-growing companies. Dennis's deep knowledge of Lennox systems and Manhattan's demanding commercial environments drives the company's commitment to quality, speed, and integrity on every project.
Service Manager
Thomas leads Denair HVAC's service operations across Manhattan and the broader NYC metro area, ensuring technicians respond fast and clients experience minimal disruption during Lennox RTU repairs. He coordinates scheduling, technician dispatch, and customer communication with precision — a critical role when managing same-day service commitments across Manhattan's dense commercial landscape. Thomas's focus on reducing downtime and maintaining consistent service quality has been central to Denair's reputation for reliability. His operational approach ensures every Lennox rooftop repair is completed to code, on schedule, and with clear communication from first contact to final sign-off.
Application Engineer
Ramil is Denair HVAC's Application Engineer, responsible for designing and supporting HVAC systems tailored to each building's unique performance and efficiency requirements. For Lennox rooftop unit repairs in Manhattan, Ramil's technical expertise ensures equipment selection and repair planning are aligned with long-term reliability, energy savings, and full compliance with NYC building codes and Local Law 97 mandates. He oversees technical planning and application support, ensuring every Lennox RTU repair or upgrade delivers a solution that performs efficiently through New York's demanding seasonal temperature extremes, from summer heat waves to winter deep freezes.
Lead Estimator
Farrukh has been a cornerstone of Denair HVAC since 2010, bringing deep expertise in bid proposal preparation for HVAC projects across New York City. As Lead Estimator, he is responsible for delivering accurate, comprehensive proposals for Lennox rooftop unit repair and maintenance projects — ensuring Manhattan commercial clients receive transparent, competitive pricing from the outset. Farrukh tracks opportunities with vendors, subcontractors, and customers, and his value engineering approach has helped Denair clients save significantly on HVAC budgets. His meticulous process ensures scope clarity, alternates, and revisions are always provided so clients make fully informed decisions.
A well-maintained Lennox rooftop HVAC system typically lasts 15 to 20 years. Lifespan depends on usage intensity, Manhattan's demanding climate swings, and maintenance frequency. Units that receive annual preventive maintenance, timely repairs, and filter changes consistently outlast neglected systems. Denair's proactive maintenance plans are designed to push your Lennox RTU to its maximum service life while maintaining peak efficiency.
Speak with a certified Denair HVAC technician for a free, no-obligation consultation.
Denair HVAC provides Lennox rooftop unit repair services across Manhattan and the greater New York metro area.
11 Regions
Service Area
24/7
Emergency Availability
Within 4 Hours
Response Time
Contact us to confirm coverage and schedule your Lennox RTU repair today.
Recognized as one of America's fastest-growing companies
All technicians hold full OSHA safety certification
Licensed Mechanical/HVAC Contractor registered in New York
Fill out the form below and a Denair HVAC specialist will reach out to schedule your free estimate and confirm same-day availability for your Manhattan location.
For immediate assistance, feel free to give us a direct call at 718-791-5074 You can also send us a quick email at
For immediate assistance, feel free to give us a direct call at 718-791-5074 You can also send us a quick email at