Some homes have HVAC units and some homes use heat pumps to heat their homes.  If you are unfamiliar with what exactly a heat pump is, Energy.gov offers a brief explanation, " For climates with moderate heating and cooling needs, heat pumps offer an energy-efficient alternative to furnaces and air conditioners.
Like your refrigerator, heat pumps use electricity to move heat from a cool space to a warm space, making the cool space cooler and the warm space warmer. During the heating season, heat pumps move heat from the cool outdoors into your warm house and during the cooling season, heat pumps move heat from your cool house into the warm outdoors. Because they move heat rather than generate heat, heat pumps can provide equivalent space conditioning at as little as one quarter of the cost of operating conventional heating or cooling appliances."  A heat pump can actually be a very energy efficient choice for homes that are in moderate climates.  Heat pumps, just like HVAC systems, require routine maintenance in order to continue to operate efficiently and effectively.  You can hire a professional to inspect your heat pump once a year to ensure that everything is in working order.  They will inspect things like ducts, filters, and coils as well as check for duct leakage, verify airflow, check for refrigerant leaks, inspect the electric terminals, lubricate motors and verify correct thermostat operation.  There is some basic maintenance of heat pumps that every home owner can do to ensure that heat pumps are properly and safely functioning.  Heat pumps have filters that need to be changed, usually about once per month.  Your heat pump owner's manual will offer specific instructions for how often you should change your filters.  By changing heat pump filters, you keep your heat pump running efficiently which will extend the life of your heat pump and maximize energy savings each month.  Regularly check the area around your heat pump to make sure debris, weed and plants have not overgrown or built up near your heat pump as this can reduce airflow to the heat pump and decrease efficiency as well.  Energy.gov also notes that a properly maintained heat pump does make a difference in energy use, "Like all heating and cooling systems, proper maintenance is key to efficient operation. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10% to 25%."  When you do these things, and hire a professional to inspect the more intricate details of your heat pump, you can maintain efficiency, save money and keep your home nice and warm all winter long.