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All refrigerated air conditioners, whether individual room units or central systems, operate according to the same principle: they extract heat and moisture from the room air, cooling and dehumidifying it, then return the air to the room. Refrigerant, the same sub-stance that’s used in a refrigerator, circulates through the system.

How refrigerated systems work. Inside a refrigerated air conditioner are a compressor, evaporator or cooling coils, a condenser, and connecting tubing; all are filled with refrigerant. Liquid refrigerant forced through a nozzle expands and partially vaporizes into a gas. The gas then flows through the evaporator coils, cooling the coils so they extract heat and moisture from the room air (the moisture condenses on the coils).

The warm gas then flows into the compressor, where the gas is heated by compression so it exceeds the outside temperature. From the compressor, the hot gas enters the con-denser. There, the hot condenser coils dissipate heat to the outside, and the gas condenses into a liquid, ready to repeat the cycle.

A Typical Room Air Conditioner

Types of refrigerated air conditioners. One type, a room air conditioner, is very easy to operate; units can be installed in as many rooms as needed. Another type is central air conditioning, which either can be an independent system with its own blower and ducts or can be combined with a forced warm-air heating system, in which case it uses the same blower and ducts as the heating system.

Room air conditioners
A room air conditioner is mounted in a window or wall; most of the unit projects outside the house.

A blower in the unit sucks warm room air through a filter protected by a large inlet grill on the front of the unit; cool, dehumidified air returns to the room through outlet grills. Water condensing on me evaporator coils drains outside, and a fan blows outside air around the condenser coils to dissipate heat.

Cleaning the Filter

Cleaning the Condenser Coils

Little maintenance is required. During the cooling season, clean the filter and condenser coils every month (see facing page, bottom); replace the filter as necessary. You can reach the filter either through a slot on the side or top or by removing the grill. To reach the condenser, remove the back of the outside housing. Problems with the refrigeration system are best left to a professional.

Central air conditioners
Though the initial expense is higher, central air conditioning is generally more efficient, quieter, and less costly in the long run than individual room units.

In a house without forced warm-air heat, a central air conditioner can be a single unit installed next to the house or a split unit, with the condenser and compressor outdoors and the evaporator and blower inside.

For a house heated with forced warm air, the most economical installation is a split system (see at right). The evaporator is mounted in the plenum of the furnace, and the condenser and compressor are located outside the house.

A Split-Type Central Air Conditioner

To ensure efficient operation clean the filter every month during the cooling season; replace the filter as necessary Check that the condensate drain is clear and that the condense and evaporator coils are clean. When you vacuum the coils, be careful not to damage or deform the fins.

For problems with the operation of your air conditioning system, see the chart below. Call in a professional to repair the refrigeration system.

By : E-book Home repair

Air conditioners are a blessing in hot climates. Not only do they cool the air, but many dehumidify and filter the air as well. The two most common types of air conditioning systems for the home are evaporative and refrigerated. Both can cool just a single room or an entire house; most types are controlled by a thermostat.

Evaporative air conditioners, also called swamp coolers, work well in dry desert regions. Refrigerated units, though more expensive to purchase than evaporative ones, are the only way to cool air in other than desert climates. Included in the category of refrigerated units are both room air conditioners, fitted into a wall or window, and central air conditioning. An-other type of refrigerated system, a heat pump, cools and heats a house (see below).

The energy cost of most air conditioning systems is high. For this reason, it’s important that your system be properly maintained and, if necessary serviced by a professional.

The descriptions below and on the next pages will help you become familiar with the different systems. To ensure long, reliable operation, be sure to follow the few simple maintenance steps outlined for your particular system.

Evaporative Air Conditioners
In hot, dry areas, evaporative air conditioners are the most efficient way to cool a home. The unit is mounted in full sun on the roof or beside the house.

Inside the unit, water is sprayed on porous, absorbent blankets. Hot out-side air pulled through the blankets by a blower causes the water to evaporate, cooling the air. The cool air then enters the house, forcing stale air out through open windows.

With conscientious maintenance, you can expect few problems. At the beginning of each cooling season, and more often if you see a mineral buildup from the evaporated water, thoroughly clean the unit, oil the pump and blower, and replace the blankets. Also, check and adjust the blower belt; if it’s cracked or worn, replace it as for a belt in a warm-air furnace.

A Typical Evaporative Air Conditioner

How a Heat Pump Works
Basically, a heat pump is a refrigerated air conditioning system in which the air flow is instantly reversible.

During warm weather, the pump draws heat from the air inside the house, cooling it and transferring the heat to the outside or to a large solar mass. During cool weather, the flow is reversed heat extracted from the outside air or from a large solar mass heats the air inside the house. Once the thermostat is set at the desired temperature, the heat pump automatically heats or cools your house as required.

In climates where temperatures below 0F are common, either electric heating elements or some other supplemental heat source is required. Whenever the heat pump cannot ex-tract enough heat from the outside air, the supplemental system turns on.

If you add an electric air cleaner and, to compensate for dry winter air, a humidifier, your heat pump system will provide clean air at the correct temperature and humidity for 24 hours a day.

Be sure to keep the outdoor portion of the heat pump free of snow and debris. Occasionally check the blower and filter, and replace the filter monthly when in use.

By : E-book Home repair

Low installation cost, fast heat delivery, and reliability make forced warm-air systems a popular heating choice. The system is also very versatile, lending it-self to the addition of central air conditioning.

In this system, a blower pulls air from the rooms into the cold-air return and return duct, through a filter, and into the furnace. There the air is heated. It then flows back to the rooms through the warm-air ducts and registers.

For maximum efficiency clean the system (see below) and inspect the burner and thermo-stat. A system that’s working inefficiently can be adjusted, as explained on the facing page. For other problems, see the chart.

Caring for the system

To ensure trouble-free operation, service the system as follows:

Clean or replace the filter monthly during the heating season.

Brush and vacuum heat exchanger surfaces annually (see owner’s manual for instructions).

Clean the blower blades at the start of each heating season; add a few drops of motor oil to each oil cup if your blower is equipped with them.

A forced Warm-Sir Heating System

Check and adjust the belt alignment and tension (see illustrations below) if your furnace has a belt-driven blower. To replace a worn belt, loosen the motor adjustment bolt, remove the old belt, and attach a new one. Adjust as shown.

Examine the ducts annually for leaks; seal any leaks with duct tape.

Balancing the heat
If some rooms are too hot or too cold, try adjusting the dampers in the registers and, if your system has them, the dampers in the warm-air ducts. Leaving the thermostat at one setting, let the system run for 3 hours to stabilize the temperatures. Open the dampers wide in the coldest rooms.

Then adjust the dampers room by room until temperatures are balanced. Wait half an hour after each adjustment before rechecking or readjusting. Speeding up the blower may help heat chronically cold rooms. Adjust the motor pulley of a belt-driven blower (see facing page, bottom) or, for a direct-drive blower, change the electrical connections (see owner’s manual).

Three Blower Adjustments

Setting the fan control

If you’re chilled by a blast of cool air when the blower turns on, try adjusting the fan control (see at right). A word of caution: If your furnace has a combination fan and limit control, do not touch the pointer on the limit control side. This pointer turns off the furnace if the maximum allowable air temperature is exceeded.

As the blower turns on, hold your hand in front of the warm-air register farthest from the furnace. Ideally your hand should feel neither cooler nor warmer. If it feels cooler, uncover the control and move the fan control’s ON pointer a few degrees higher. Check and readjust as necessary Conduct a similar test to increase fuel efficiency but check the air just be-fore the blower shuts off. If your hand feels warmer, move the OFF pointer a few degrees lower.

Setting the Fan Control

By : E-book Home repair