How do central heating and cooling systems work?

Understanding how heating and cooling systems work can save you time, money, and energy by helping you know when to call a professional technician.

Most air conditioners work with the use

of Freon or refrigerants, which cool down the air inside the system's coils. First, a compressor turns the refrigerant into a hot, high-pressure gas that loses heat as it travels through the coils causing the gas to condense into a hot liquid. As the liquid expands it becomes a cold, low-pressure gas, which absorbs heat and returns to the compressor to begin the cycle again. The cool air is pumped into your home by motors and fans while hot air is extracted.

Heat pumps are energy efficient systems that both heat and cool. In the winter, they work in reverse of the air conditioning by extracting cold air and pumping warm air into the home. Another kind of heating system is heat strips, which contain elements that heat up providing hot air to be distributed throughout the home with the use of fans.

According to Annette Floridia, a customer service representative for Precision Aire, heat pumps are more popular in the warmer southern states, while the climate in northern regions sometimes requires the more expensive heat strip systems. "Heat pumps can usually keep a home warm when the weather outside is as low as the 20's. Below that, sometimes the heat pump just cannot make your house as comfy or as snug as you want. That is where your heat strips come into play. In the northern states oil heat and gas heat are used more often," she says.

Central heating systems work by way of a boiler or furnace usually located in the home's basement. In the case of boilers, water is heated and the steam is sent to radiators throughout the home. In the case of furnaces, air is heated and the warm air is pumped through a system of air ducts to heat the home. Thermostats located in the home control the temperature and operation of the heating system.

Air duct systems are the most common type of heating and cooling system in modern homes. Of these, there are two types: gravity and forced-air. Gravity systems rely on the tendency of heat to rise naturally. There are no fans in this type of system. Instead the ducts are usually large and deliver warm air to locations above the furnace. Systems that have a blower or heat pump are forced-air systems.

Central heating and air systems share the same air ducts for both heating and cooling and usually share the same thermostat. These systems also have the capability of humidifying and electronically cleaning the air that is delivered to the home. Most heat pumps run on electricity and include the following components: an outdoor condenser, refrigerant-filled coils, an indoor air handler, a fan blower operated by a motor, heating elements, an air duct system that runs throughout the home to registers located in each room, a return air system, and air filters. Understanding how the heating and cooling system works in your home can help you to pinpoint problems when they arise.