Basics of Heating and Cooling Systems

Heating and cooling is an important part of our daily lives as it comforts us by heating and cooling the surroundings we live, depending on the area we live, and also depending on the specific season. (autumn, winter, spring, or summer). We expect our heating systems to keep us warm during the winter, and we depend on air-conditioning to keep us cool during the hot summer days. Therefore, it is important to know how the basics of how heating and cooling systems function.

How Heating and Cooling Systems Work

Heat Pumps

Air Conditioners
All climate-control systems have three basic components: a source of warmed or cooled air, a means of distributing the air to the rooms being heated or cooled, and a control used to regulate the system (e.g., thermostat). The sources of warm air, such as a furnace, and cool air, such as an air conditioner, in a house often use the same distribution and control systems. If your house has central air conditioning, cool air probably flows through the same ducts that heat does and is regulated by the same thermostat. When a heating or cooling system malfunctions, any of these three basic components may be causing the problem.
 
Both heating and air conditioning work on the basic laws of thermodynamics that heat always moves from a warm object to a cooler one. Furnaces and heaters put heat into the air to make your home warmer; air conditioners remove heat to make your home cooler.
 
All heating and cooling units burn fuel. Air conditioners use electricity. Most home heating systems use gas or fuel oil; other systems use electricity. The heat pump -- an electrically powered climate control unit -- both heats and cools the air. In summer it extracts heat from the air inside your home. In winter it pulls heat from the air outside and uses this heat to warm the air inside the house.
 
When the furnace is turned on, it consumes the fuel that powers it. It can be gas, oil, or electricity. As fuel is burned, heat is produced, and subsequently channeled to the living areas of your home through ducts, pipes, or wires and then is blown out of registers, radiators, or heating panels.
 
Older systems use the heat they produce to heat water, which in turn heats the air in your home. These systems use a boiler to store and heat the water supply, which is then circulated as hot water through pipes embedded in the wall, floor, or ceiling. This method is quite expensive today.
 
When an air conditioner is turned on, electrical power is used to cool a gas in a coil to its liquid state. In most systems, a common refrigerant is used. (e.g. R134a, Tetrafluoroethane). Warm air in a house is cooled by contact with the cooling coil, and this cooled air is channeled to the rooms of your home through ducts and out registers or -- in the case of room air conditioners -- directly from the unit itself.
 

HVAC Distribution Systems 

Once air is warmed or cooled at the HVAC source, it must be distributed to the various rooms of a building or house.. This can be accomplished with the forced-air, gravity, radiant systems, or hydronic systems.

See top of the page for more detailed information of HVAC Distribution Systems mentioned above.