Air conditioning systems can seem to be a confusing, complicated system of wires. motors and air ducts to most people. But they can be easily understood if your know how all the parts function. Most Texas homes have central air conditioning systems, which are the best cooling solution for our homes. It’s the quietest, best performing and most comfortable type of system. However, the system must be sized properly for the home. If it is too large it will not perform well and will not adequately dehumidify and it may short cycle.
First, we need to understand the individual parts of our air conditioning system and some common terms.
Air Handler – The part of the system which moves heated or cooled air throughout the ductwork.
Btu – British thermal unit is used to measure how much energy and air conditioning unit uses. It is the amount of heat needed to raise the temperature of one pound of water (about one pint) by one degree F.
Compressor – It is a pump that pressurizes refrigerant.
Condenser – Facilitates heat transfer
Evaporator Coil – The portion of the system that is located inside the home and functions as the heat transfer point for warming or cooling indoor air.
Expansion Valve – regulates refrigerant flow into the evaporator
Outdoor Coil/Condensing Unit – The portion of a heat pump or central air conditioning system that is located outside and functions as a heat transfer point for dispelling heat to the outside air.
Refrigerant – A liquid contained within the coils of an air conditioner which cools and dehumidifies indoor air.
SEER – Seasonal Energy Efficiency Ratio is a measure of an air conditioner’s cooling efficiency. The higher the SEER rating, the more efficient the product. The government’s established minimum SEER rating for air conditioners is 10.
Short Cycle – The compressor constantly shuts on and off frequently. It may be caused by a faulty or obstructed thermostat, leaking refrigerant, icy coils or an HVAC system that is too big for the home.
Split System – A heat pump or central air conditioning system with components located both inside and outside the home. The most common design for home use.
Central air conditioning systems are made up of two sections, the condensing unit and the evaporative unit, connected by tubes full of refrigerant. The condensing unit is the boxy unit outside the house. It contains the compressor, condensing coils as well as condensing fan. The evaporation unit typically sits in the attic of your furnace so the air conditioning can use the same ductwork as your heating system. The evaporative unit consists of the evaporator coil and expansion valve.
The refrigerant is pumped through the air conditioner’s entire system. It changes state from a gas vapor to a liquid as it absorbs heat from your house and radiates that heat to the outside. The compressor pumps the refrigerant through all the components in a big loop. The refrigerant enters the compressor at a lower pressure as warm vapor and leaves as a higher pressure hot vapor. From the compressor, the hot refrigerant vapor moves on to the condenser. In the condenser, the hot refrigerant vapor is cooled by air blowing over condensing coils by the condenser fan as it moves through the coils. As the refrigerant cools, it changes state from a hot vapor to a hot liquid at a high pressure. Then, it moves onto the expansion valve. The hot liquid refrigerant passes through a tiny opening at high pressure in the valve on one side, it emerges as a cool low pressure mist on the other side. As a gas expands, it cools.
The low pressure colder liquid leaving the expansion valve now goes through the evaporator coil located in the attic unit of your furnace. The hot air from the house blows across the evaporator coil and warms up the coil removing the heat from the air. The cooled air blows back into your home. As the refrigerant heats up, it boils and changes from a cold liquid and evaporates into a warm vapor. From there, it moves back outside to the compressor and exterior condensing unit and the cycle continues.
It is possible that you may have a split or ductless air conditioner. The split system is sometimes called a “packaged terminal air conditioner” (PTAC). Occasionally, they may be used in a home. More often, you find them in hotels, motels and sometimes in apartments. The principle is the same as central air conditioning, but it uses much smaller units. The split system has two packages or terminal units and refrigerant tubing passes through the wall connecting the units. One terminal package is the condensing unit located on the exterior and includes the compressor, condenser and condenser fan. The other package is the evaporative unit located on the interior and handles air cooling and distribution. The internal evaporation unit includes the fan, expansion valve and evaporator coil.
If you’re having a air conditioning problem, you should call your certified HVAC company. Their certified technicians can explain the differences between systems and product types and make the necessary repairs. Ask about discounts or rebates from the manufacturers. Your certified HVAC technician may also have additional suggestions and may have specials on equipment or other services. Many also have service plans, like Abacus BAM Plan, that can help save you money on service calls and provide annual tune-ups.