Brennan Heating & Cooling specializes in the provision of heating, ventilation, and air conditioning (HVAC) services. The company offers a range of products and services including Heil Furnace and Air Conditioning Systems, Mitsubishi or Fujitsu Systems, and Unit Heaters for garages. They also provide maintenance services such as professional HVAC technician inspections and advice on maintaining the efficiency of HVAC systems, such as ensuring the condensing unit is free of debris and changing furnace filters regularly. Additionally, Brennan Heating & Cooling offers Mini-Split Ductless Systems, which consist of an air-handling unit inside the home and a condenser unit outside.