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.
"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 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!"
"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."
"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."
"Amazing HVAC vendor who is doing multiple accounts for my company."
"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"
"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!"
"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."
"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."
"Amazing HVAC vendor who is doing multiple accounts for my company."
"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"
"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!"
"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."
"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."
"Amazing HVAC vendor who is doing multiple accounts for my company."
"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!"
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 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.
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.
For immediate assistance, feel free to give us a direct call at 718-791-5074.