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Comprehensive HVAC Solutions for Your Home and Business

When indoor comfort matters most, Mannix Heating and Cooling delivers professional heating, ventilation, and air conditioning services throughout Gaithersburg, MD, Chantilly, VA, Treasure Island, FL and their surrounding areas! Don’t Panic, Call Mannix!

$20 Off a Service or Repair Call

Service calls are normally $120.00

Cannot be combined with other promotions
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$100 Off Whole Home Air Purifier

Call (703) 777-9211 for more information.

Cannot be combined with other promotions
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$300 Off Stand-By Home Generators

Call (703) 777-9211 for more information.

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$20 Off an Emergency Service or Repair Call

Service calls are normally $225.00

Cannot be combined with other promotions
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$20 Off Preventative Maintenance Plans

Call (703) 777-9211 for more information.

Cannot be combined with other promotions
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10% Off Service Calls for First Responders, Veterans & Active Military

Call (703) 777-9211 for more info

Cannot be combined with other promotions
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We’re in Your Neighborhood

Whether you’re in Gaithersburg, MD, Chantilly, VA, or Treasure Island, FL, our local teams are ready with a 24-hour answering service and experienced technicians who keep your systems running when you need them most.

Gaithersburg, MD

7824 Beechcraft Ave
Gaithersburg, MD, 20879
(301) 260-6000

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Chantilly, VA

26955 Gum Spring Road
Chantilly, VA, 20152
(703) 777-9211

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Treasure Island, FL

10625 1st Street E. Suite 200
Treasure Island, FL, 33706
(727) 999-7002

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Award-Winning Service You Can Trust

Our family-owned operation has built an outstanding reputation for customer service since 2010, combining technical expertise with honest, fair business practices that have earned recognition as a Carrier Factory Authorized Dealer. We take pride in treating every customer’s home or business as if it were our own, ensuring quality workmanship and transparent communication throughout every project. Just look us up on Angie’s List or read what others are saying about us on Google or Yelp to understand why homeowners and businesses trust us with their indoor climate control needs.

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Comprehensive Climate Control Solutions

Our comprehensive approach encompasses everything from routine maintenance to complete system overhauls, ensuring optimal performance throughout every season. We specialize in both residential and commercial applications, understanding that each environment presents unique challenges requiring customized solutions.

Customer Reviews
We were in desperate need of a fix on our AC system during the July heatwave. The issue arose on a Saturday. Mannix came to the rescue in short order, fixed it, and at a reasonable price. Silvio G was the technician, and he was GREAT. We would definitely use Mannix again!
Customer Reviews
I have been using Mannix for years. They have replaced my HVAC system and I have them do maintenance twice a year. The past couple of visits have been done by Ramiro. He is professional, polite, knowledgeable, and very helpful in assisting me with tips on the best ways to operate my system. Today,...
Patricia Ryan Leave a Review
Customer Reviews
Mannix proved very responsive in fixing my A/C system. The tech, Erick, was very professional by taking the time showing and explaining to me the system problem prior to taking action replacing the coil. Ashleigh, customer service, was excellent in addressing and following through on concerns in...
Gary Hendricks Leave a Review
Customer Reviews
Been a happy Mannix customer for a few years now, but recently had them replace our aging HVAC system. The whole process was very painless, from Eric helping us decide which system was right for our home, to the efficient and professional installation by Billy and Matt. I am very pleased with the...
Philip Slingerland Leave a Review
Customer Reviews
Mannix has always been professional from service calls to repairs and replacements. The technicians are always polite and knowledgeable. They consistently exceed our expectations.
Wendy Collins Leave a Review
Customer Reviews
They were lifesavers!!! My furnace went out and after three days of dealing with the home warranty company and the unscrupulous vendor they sent to my home, I called Mannix. The service technician was friendly, efficient but most of all honest. He found the problem after twenty minutes, saving...
Shondra J ones Leave a Review
Customer Reviews
Before dealing with Mannix I used two very well-known and “reputable” HVAC companies who did nothing but rip us off over the years. I was frustrated and found Mannix Heating & Cooling about 10 years ago. They installed a new HVAC system in my old home, and installed a water...
Customer Reviews
I’ve been using Mannix for years and have never been disappointed. They’ve replaced my HVAC, hot water heater and installed a humidifier on my furnace. Whenever I need them, they can get me on the schedule in a timely manner. All the personnel are great and I trust Jerry and his team...
Rachel Craft Leave a Review
Customer Reviews
I contacted Mannix from a referral of a friend who has benefitted from the excellent service this company provides. I found out a couple I know in Vienna had their heat pump stop working a few months ago and needed to be replaced. I called up the Mannix office later in the day on Monday 11/30/20...
Lynne Wilson Leave a Review
Customer Reviews
My 24-year-old heat pump finally decided to stop working. I sent a request for a replacement estimate late one night through the Mannix website and received a phone call early the very next morning to set up an appointment. Eric Holzworth stopped by my house the next day to go over my options. He...

Heating Services and System Expertise

Our heating division handles all major equipment types including gas furnaces, electric heat pumps, dual-fuel systems, boilers, and high-velocity heating configurations. Modern heating systems incorporate sophisticated control boards, variable-speed blowers, and modulating gas valves that require specialized diagnostic equipment and technical knowledge for proper service. We perform comprehensive heat exchanger inspections using advanced camera technology to detect microscopic cracks that could lead to carbon monoxide exposure. Our technicians analyze combustion efficiency, measure temperature rise across heat exchangers, and verify proper venting to ensure safe operation while maximizing fuel economy.

Heating Services

HVAC Maintenance

Mannix Rewards

Receive up to $100 Mannix Heating & Cooling Visa® Prepaid Card

Customer Referral Program

Reliable HVAC Services When You Need Us

Our experienced technicians provide comprehensive heating, cooling, and air quality solutions to keep your home comfortable year-round.

Heating

No matter what type of heating system you rely on, whether at the beginning or toward the end of it’s service life, the key to safe, efficient, and reliable performance is regular, professional maintenance.

Cooling

Anything less than perfect performance from your cooling system is unacceptable. Even minor issues impact your everyday life, causing discomfort, aggravation, and higher running costs.

Pool Heat Pumps

Extend your swimming season and enjoy comfortable water temperatures year-round with an energy-efficient pool heat pump. Mannix Heating & Cooling will find the right pool heating solution for your backyard oasis.

Pool Heater Installation

Make the most of your pool investment with a professionally installed pool heater that keeps water at the perfect temperature throughout the season.

Water Heaters

Reliable hot water is essential for your daily comfort and convenience. Whether you need a traditional tank water heater, a tankless system, or a heat pump water heater, we will find the right solution for your home and budget.

Light Commercial

Reliable climate control is essential for your business operations and customer comfort. Whether you need rooftop units, split systems, or packaged HVAC solutions, we will find the right commercial system for your facility and budget.

Learn More About Mannix Heating and Cooling

Regular heating maintenance extends equipment lifespan significantly beyond manufacturer warranties. During seasonal tune-ups, we clean burner assemblies, adjust gas pressure to manufacturer specifications, test safety controls including limit switches and flame sensors, and verify proper airflow across heat exchangers. These preventive measures typically reduce heating costs by fifteen to twenty percent while preventing unexpected breakdowns during peak winter demand when replacement parts may face supply chain delays.

Air conditioning systems have evolved dramatically with the introduction of variable-speed compressors, smart thermostats, and environmentally friendly refrigerants. We service all cooling equipment including central air conditioners, ductless mini-splits, heat pumps, and high-velocity systems designed for homes without traditional ductwork. Our cooling services address common issues like refrigerant leaks, frozen evaporator coils, failed capacitors, and worn contactors that compromise system efficiency.

The EPA’s phase-out of R-22 refrigerant has created challenges for older system maintenance, requiring careful retrofit planning or strategic replacement timing. We help customers navigate these transitions by analyzing repair versus replacement economics, considering factors like SEER ratings, equipment age, and available utility rebates. Modern systems achieving 20+ SEER ratings can reduce cooling costs by forty percent compared to units installed before 2006, making upgrades financially attractive despite initial investment requirements.

Indoor air quality directly impacts respiratory health, sleep quality, and overall wellbeing, particularly in Gaithersburg, MD, Chantilly, VA, Treasure Island, FL and their surrounding areas where seasonal allergens and humidity fluctuations create challenging conditions. We install and service comprehensive air quality systems including:

  • HEPA filtration systems capturing particles down to 0.3 microns including viruses, bacteria, and allergen proteins
  • UV germicidal lights neutralizing biological contaminants within ductwork and on evaporator coils where moisture promotes microbial growth
  • Whole-house humidifiers and dehumidifiers maintaining optimal 30-50% relative humidity levels year-round

Professional air quality assessments identify specific contaminants affecting your environment, whether volatile organic compounds from building materials, combustion byproducts from attached garages, or biological allergens from pets and outdoor sources. We design targeted solutions addressing identified concerns while integrating seamlessly with existing HVAC equipment.

Beyond traditional HVAC services, we provide comprehensive home comfort solutions including electrical services, water heater installation, pool heat pump systems, and standby generator installation. These interconnected systems require coordinated planning to maximize efficiency and reliability. Our Aeroseal duct sealing service addresses the twenty to thirty percent energy loss typical in older ductwork systems, using advanced polymer technology to seal leaks from inside ducts without invasive demolition.

If a problem occurs with your heating or cooling system, don’t panic, call Mannix! Our rapid response capabilities, extensive parts inventory, and manufacturer relationships ensure minimal downtime when equipment failures occur. We maintain strong partnerships with Carrier and Honeywell, providing access to premium equipment lines and extended warranty options that protect your investment while ensuring long-term performance reliability throughout Gaithersburg, MD, Chantilly, VA, Treasure Island, FL and their surrounding areas and surrounding communities. We also service a variety of makes and models including Rheem.

Owner, Jerry Mannix

The Proud Recipient of Federated Insurance’s ACCA Super S.T.A.R. Award!

Customer First Award Winner: Mannix Heating & Cooling
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