CENTRAL AIR CONDITIONERS AND HEAT PUMPS

Central air conditioners and heat pumps are designed to cool the entire house. In each system, a large compressor unit located outside drives the process; an indoor coil filled with refrigerant cools air that is then distributed throughout the house via ducts. Heat pumps are like central air conditioners, except that the cycle can be reversed and used for heating during the winter months. With a central air conditioner, the same duct system is used with a furnace for forced warm-air heating.

DUCTLESS MINI-SPLIT AIR CONDITIONERS

Mini-split systems, can be an attractive option for room additions and for houses without ductwork. Like conventional central air conditioners, mini-splits use an outside compressor/condenser and indoor air handling units. The difference is that each room or zone to be cooled has its own air handler. Each indoor unit is connected to the outdoor unit via a conduit carrying the power and refrigerant lines. Indoor units are typically mounted on the wall or ceiling. The major advantage of a ductless mini-split is its flexibility in cooling individual rooms or zones. By providing dedicated units to each space, it is easier to meet the varying comfort needs of different rooms. By avoiding the use of ductwork, ductless mini-splits also avoid energy losses associated with central forced-air systems.

FURNACES

A furnace works by blowing heated air through ducts that deliver the warm air to rooms throughout the house via air registers. This type of heating system is called a ducted warm-air or forced warm-air distribution system. It can be powered by electricity, natural gas, or fuel oil.

BOILERS

Boilers are special-purpose water heaters. While furnaces carry heat in warm air, boiler systems distribute the heat in hot water, which gives up heat as it passes through radiators or other devices in rooms throughout the house. The cooler water then returns to the boiler to be reheated. Instead of a fan and duct system, a boiler uses a pump to circulate hot water through pipes to radiators. Important boiler controls include thermostats and valves that regulate circulation and water temperature. As with furnaces, condensing gas-fired boilers are relatively common, and significantly more efficient than non-condensing boilers

HEAT PUMPS

Heat pumps are just two-way air conditioners. During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outside. In winter, the heat pump reverses this trick, scavenging heat from the cold outdoors with the help of an electrical system, and discharging. Installation for this type of system typically consists of two parts: an indoor unit called an air handler and an outdoor unit similar to a central air conditioner, but referred to as a heat pump. A compressor circulates refrigerant that absorbs and releases heat as it travels between the indoor and outdoor units.