Long Island's weather swings—from humid summers to bitter winters—demand a reliable HVAC partner you can count on year-round. Denair HVAC brings over 19 years of expertise in heating, cooling, and emergency repairs across Nassau and surrounding areas. Licensed technicians, free estimates, and same-day service mean your home or business is never left uncomfortable.
Comprehensive heating, cooling, and ventilation solutions for Long Island homes and businesses—handled by certified technicians.
Expert repair and maintenance for all residential air conditioning and heating equipment. Licensed technicians service, maintain, install, and repair AC units, furnaces, water heaters, and ductwork to keep your system running optimally.
Round-the-clock emergency HVAC repairs with same-day response—usually within 4 hours. Certified technicians arrive fully equipped to diagnose and fix issues on all major brands from 1/2 to 100 tons of cooling capacity.
Proactive maintenance plans designed to extend system lifespan, reduce energy costs, and prevent surprise breakdowns. Free preventive maintenance for up to 18 months on all new installations, with annual contracts available.
Turnkey commercial and residential HVAC installation with end-to-end project management. Includes equipment, ductwork, piping, and controls—delivering projects on time, within budget, and saving clients up to 35% through value engineering.
Modernize outdated equipment with targeted retrofits and expert system tune-ups. Optimize performance, enhance comfort, and meet current energy standards without requiring a full system replacement.
Smart HVAC controls and automation solutions that significantly reduce energy costs and environmental impact—ideal for Long Island property owners seeking lower utility bills and greener operations.
Long Island's hot, humid summers and cold winters put serious demands on heating and cooling systems. Denair HVAC's licensed technicians bring over 19 years of hands-on experience servicing all makes and models across Nassau and the broader New York Metro Area. From emergency repairs completed within 4 hours to comprehensive preventive maintenance plans, we deliver upfront pricing, free estimates, and a quality guarantee—so your comfort is never compromised, no matter the season.
See how Long Island homeowners and businesses have benefited from Denair HVAC's expert service and repairs.
"Denair is the most dependable HVAC service company in New York!"
"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..."
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"Crew was respectful, fast, and left our place spotless. Five stars."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"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!"
"These guys are the best. Installed my central air condition. They are quick, thorough and honest! I definitely recommend them."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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!"
"Impeccable install. You can tell they're pros the moment they walk in."
"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."
"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."
"excellent work and quality"
"Denair is the most dependable HVAC service company in New York!"
"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..."
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"Crew was respectful, fast, and left our place spotless. Five stars."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"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!"
"These guys are the best. Installed my central air condition. They are quick, thorough and honest! I definitely recommend them."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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!"
"Impeccable install. You can tell they're pros the moment they walk in."
"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."
"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."
"excellent work and quality"
"Denair is the most dependable HVAC service company in New York!"
"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..."
"I am very pleased with the service and professionalism we receive from all the techs and staff at Denair."
"Crew was respectful, fast, and left our place spotless. Five stars."
"Really great to work with, awesome staff, happy to work with them anytime again in the future! Highly recommend."
"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!"
"These guys are the best. Installed my central air condition. They are quick, thorough and honest! I definitely recommend them."
"I was able to upgrade my cooling towers through the help of Denair and I did love their Service rendered, Wonderful Experience."
"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!"
"Impeccable install. You can tell they're pros the moment they walk in."
"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."
"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."
"excellent work and quality"
From Nassau to Brooklyn, here's what sets Denair HVAC apart from the competition on Long Island.
Our technicians respond to Long Island service calls usually within 4 hours, any day of the year.
OSHA-certified, manufacturer-trained technicians who meet New York's stringent HVAC licensing standards.
Free estimates with fixed proposal pricing—all unintended costs are absorbed at our expense, never yours.
Serving Nassau, Queens, Brooklyn, and greater Long Island with a dedicated team of 28 experienced professionals.
Experienced professionals dedicated to keeping Long Island comfortable year-round.
Founder & CEO
Dennis founded Denair HVAC in March 2007 with a single used truck and a vision to deliver honest, affordable HVAC service across New York. With over 17 years of hands-on industry experience, he has grown the company from a one-man operation into a $2M+ revenue enterprise recognized by Inc. 5000 as one of America's fastest-growing companies. Dennis leads Denair's strategic vision, driving the team's culture of transparency, commitment, and client-first service that Long Island and New York Metro customers rely on every day.
Service Manager
Thomas leads Denair HVAC's service operations across Long Island and the New York Metro Area, ensuring fast response times, efficient technician scheduling, and consistent service quality on every job. He coordinates field teams and customer communication to minimize downtime and deliver a seamless experience from the first call to final sign-off. Thomas's operational focus is what drives Denair's ability to respond to emergency HVAC calls usually within 4 hours—keeping homes and businesses comfortable no matter the season or the urgency of the situation.
Application Engineer
Ramil designs and supports HVAC systems tailored to each building's unique performance and energy efficiency needs across Long Island and New York. He oversees equipment selection, technical planning, and application support to deliver code-compliant solutions that maximize reliability and minimize long-term operating costs. Ramil's engineering expertise ensures that every installation and upgrade recommendation is backed by precise technical analysis—whether it's a single-family Nassau home or a large commercial property—resulting in systems that deliver lasting comfort and measurable energy savings.
Lead Estimator
Farrukh has been a cornerstone of Denair HVAC since 2010, bringing deep expertise in bid preparation and cost estimation to every project the company undertakes on Long Island and throughout the New York Metro Area. As Lead Estimator, he is responsible for delivering comprehensive, timely proposals and tracking opportunities with vendors, subcontractors, and clients. His meticulous approach to value engineering has been instrumental in saving Denair clients hundreds of thousands of dollars on HVAC installations—ensuring competitive pricing without compromising on quality or compliance.
A Reznor heater is a brand of commercial and industrial gas-fired unit heaters widely used in warehouses, garages, and large facilities. They are known for their durability and efficient forced-air heating output. Denair HVAC technicians are trained and certified by major manufacturers and can service, repair, or replace Reznor heating units across Long Island and the New York Metro Area.
Speak with a Long Island HVAC expert today—consultations and estimates are always free.
Denair HVAC proudly serves Long Island and the wider New York Metropolitan Area with fast, reliable HVAC service.
11+ Regions
Service Area
24/7 On Call
Emergency Availability
4.7★ Rated
Customer Rating
Contact us to confirm coverage in your area and get a free same-day estimate.
Named one of America's fastest-growing companies.
All technicians hold OSHA safety certification.
New York State licensed mechanical contractor.
Fill out the form below and a Denair HVAC specialist will reach out promptly to schedule your free estimate or same-day service call. No obligations, no hidden fees—just expert HVAC help when you need it most.
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