Central cooling and central heating are technically separate entities, but they are designed to work together and keep you comfortable all year long. The split system is the most common central cooling system. It is comprised of an outdoor section that holds a compressor (which pumps refrigerant) and condenser coil. The inside section houses an evaporator coil which is used in conjunction with an air handler or furnace.
When warm air is moved across the evaporator coil inside, the energy of heat transfers to the refrigerant. This is what creates cooler air. The cycle starts again when refrigerant is pumped back to the compressor. The heat is moved outside the house or business, along with any moisture/humidity and cool air is blown inside.
The same ductwork is shared by the cooling and heating system. The central heating systems will normally have a furnace made of up of four sections. These are; the heat exchanger, burners which burn and deliver fuel, blower and an exhaust for gas by-products. You can choose between using oil, gas or a hybrid system. Many times consumers choose this based on their personal situation and where they live. The burners found in your furnace will generate the combustion gases which are then passed through the heat exchanger. Air blows across the heat exchanger with the purpose of being warmed, and then your ducts send it around your house ensuring your climate comfort.