St. Marys and Calvert County Maryland HVAC Services   ♦   We Make Your Air Flow!

HVAC Residential Service: Serving Prince Frederick South in Calvert County and All of St Marys County in Southern MD


Heat Pumps, Heating & Cooling System Installation Services & System Types


  • Propane Furnace Installations
  • Propane Furnace Service & Repair
  • Radiant Heating Installations
  • Radiant Heating Service & Repair
  • Heat Pumps Installations
  • Heat Pump Service & Repair
  • Air Conditioning Installations
  • Air Conditioning System Service & Repair
  • Heating & Cooling Zoning
  • Heating & Cooling System Service Agreements


  • Heating & Cooling System Service & Repair
  • Heating & Cooling Air Duct Cleaning
  • Direct Heating & Cooling System Replacement
  • Heating & Cooling System Service & Repair
  • Oil Tank Installations
  • Oil Tank Service & Repair
  • Oil Furnaces Installations
  • Oil Furnace Service & Repair
  • Gas Furnaces Installations
  • Gas Furnace Service & Repair
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Our Technicians

Great Mills Heating and Air employs NATE-certified technicians who have proven their knowledge in the HVAC/R industry by passing specialized NATE certification tests. Choose Great Mills for superior installation and maintenance or service of your heating, ventilation, air conditioning or refrigeration system to get the job done right the first time. SMECO Recommends Great Mills Heating and Air as a heating and air conditioning contractor with Nationally Certified Technicians with proper insurance and licensing.


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Ask us about Geothermal Heating and Cooling Systems

Great Mills Heating and Air also installs geothermal systems for homes.

Geothermal vs. Ground Water vs. Water Furnace Geothermal energy has been used to heat and air condition buildings for several decades. Other terms for these geothermal systems include geo-thermal, geoexchange, ground-water, ground-water assisted, ground-water-source, water-to-water, and even water furnace heating and cooling. 

Geothermal heat pump technology taps the energy in the earth's surface and drive a heating and air conditioning system for both residential and commercial uses. The result is a green or natural heat pump that saves energy and benefits the environment.



We service or repair the following heating and air conditioning manufacturers. In addition, we can replace the following heating and air conditioning manufacturers with Carrier.


Airquest, Airtemp, Amana, American-Standard, Armstrong, Bard, Bryant, Carrier, Coleman, Comfortmaker, Crane, Daikin Us, Ducane, Fasco, Fraser-Johnston, Fedders, Friedrich, General Electric, Green, Colonial, International Oil Burner, Intertherm, Iron Fireman, ITT, Janitrol, Johnson Air-Ease, Lennox, Luxaire, Magic Chef, Mayflower, Mcquay, Miller, Climatrol, Payne, Peerless, Rheem, Ruud, Square D, Tappan, Trane, Westinghouse, Whirlpool, Williamson, York.


Financing Options


Great Mills Heating and Air offers various financing options:


Call the office for other options 301-994-0522.


Call Us or Email Us


for Info on SMECO Rebates and Carrier Spring Rebates On complete HVAC system installations!




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