Markool Heating & Cooling is a premier HVAC contractor locally owned and operated in Frederick, MD. Since 2016, our team of skilled technicians has offered high-quality work and emergency services with a personal touch 24 hours a day, seven days a week. Our heating company is Energy Star-certified and a member of the ACCA, our technicians are NATE-certified, and we are a Carrier Factory Authorized Dealer. We also care about our community and donate to Ducks Unlimited, a nonprofit organization dedicated to preserving the wetlands here in Maryland and throughout North America.