How Does Air Conditioning Really Work?

air conditioning cycle

How Does Air Conditioning Really Work?

As with all air conditioning equipment the principles remain the same – the heat is removed from one area and replaced with cooled dry air then the hot air is removed, normally to the outside atmosphere or ambient area. As you can see from this typical example of a air conditioning system, the ambient air is drawn over the condenser just like a ‘radiator’ as seen on auto motor vehicles but instead of water running through the cooling system it contains a refrigerant gas.
On its way around the complete system it has three stages; the evaporator contains the sub-cooled refrigerant and air blows through its veins to release the chilled dry air into the room, the condenser contains the high temperature gas that once again air is blown through the veins collecting the heat as it passes through and this is then expelled outside.
Basic Operations
A air conditioner system is able to cool a building because it removes heat from the indoor air and transfers it to the outdoors. A chemical refrigerant in the system absorbs the unwanted heat and pumps it through a system of piping to the outside coil. The fan, located in the outside unit, blows outside air over the hot coil, transferring heat from the refrigerant to the outdoor air. Most air conditioning systems have five mechanical components:
• a compressor
• a condensor
• an evaporator coil
• blower
• a chemical refrigerant
Most central air conditioning units as a split system. That is, they consist of a ‘hot’ or ‘high’side, or the condensing unit—including the condensing coil, the compressor and the fan—which is situated outside your home, and a ‘cold’ or ‘low’ side that is located inside your home. The cold side consists of an expansion valve and a cold coil, and it is usually part of your furnace or some type of air handler. The furnace blows air through an evaporator coil, which cools the air. Then this cool air is routed throughout your home by means of a series of air ducts. A window unit operates on the same principal, the only difference being that both the hot side and the cold side are located within the same housing unit.
The compressor (which is controlled by the thermostat) is the ‘heart’ of the system. The compressor acts as the pump, causing the refrigerant to flow through the system. Its job is to draw in a low-pressure, low-temperature, refrigerant in a gaseous state and by compressing this gas, raise the pressure and temperature of the refrigerant. This high-pressure, high-temperature gas then flows to the condenser coil.
The condenser coil is a series of piping with a fan that draws outside air across the coil. As the refrigerant passes through the condenser coil and the cooler outside air passes across the coil, the air absorbs heat from the refrigerant which causes the refrigerant to condense from a gas to a liquid state. The high-pressure, high-temperature liquid then reaches the expansion valve.
The evaporator coil is a series of piping connected to a furnace or air handler that blows indoor air across it, causing the coil to absorb heat from the air. The cooled air is then delivered to the house through ducting. The refrigerant then flows back to the compressor where the cycle starts over again.
Air Conditioner Filters
The most important maintenance task that will ensure the efficiency of your air conditioner is to routinely replace or clean its filters. Clogged, dirty filters block normal airflow and reduce a system’s efficiency significantly. With normal airflow obstructed, air that bypasses the filter may carry dirt directly into the evaporator coil and impair the coil’s heat-absorbing capacity. Filters are located somewhere along the return duct’s length. Common filter locations are in walls, ceilings, furnaces, or in the air conditioner itself.
Some types of filters are reusable; others must be replaced. They are available in a variety of types and efficiencies. Clean or replace your air conditioning system’s filter or filters every month or two during the cooling season. Filters may need more frequent attention if the air conditioner is in constant use, is subjected to dusty conditions, or you have fur-bearing pets in the house. If you use a disposable type filter, it’s always wise to keep several spares inside the house.

Now that you know alittle about how your air conditioning system works you should now understand the importance of air conditioning maintenance and servicing.

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AC Coil – Replace or Maintenance?

ac coil cleaning service

Air Conditioning Coil – Replace or Maintenance?

Hello.  Im Stephen and Im a master technician with Heating Repair Houston.  We keep getting the question out here:  Should I replace my indoor air conditioning coil (aka evaperator coil) or should I just get maintenance service to the ac coil?

Well, there are a few factors when considering when to maintenance or replace your indoor air conditioning coil.   The first question you should always ask yourself is: How old is the coil itself?  If you don’t know how old the ac coil Is it is always recommended to have a HVAC Service Professional come in and take a look at it for you to determine whether it will benefit you to remove the ac coil or replace it all together.  Remember, with a proper indoor ac coil cleaning a technician will remove the ac coil physically from the indoor unit all together and bring it outside and give it a chemical bath.  This method is always beneficial when the ac coil is actually in good enough shape to take the chemicals and the actual move to the outside and back where it was sitting before.  Years of rust buildup on the ac coil will put it at risk of damaging the ac coil to the point of no return.

Always replace the ac coil if rust damage is bad enough where moving the ac coil physically will potentially cause more damage than good.

Air Conditioning Cleaning / Maintenance on a indoor ac coil and outdoor ac coil is completely beneficial when the actual ac coils are in good shape.  Remember with air conditioning: AIR FLOW IS EVERYTHING!

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Choosing a Air Conditioning System

Central air conditioners circulate cool air through a system of supply ducts and return ducts. Supply ducts and air registers (example: openings in the walls, floors, or ceilings covered by grills) carry cooled air from the air conditioner to the home. This cooled air becomes warmer as it circulates through the home; then it flows back to the central air conditioner through return ducts and registers. To learn how central air conditioners compare to other cooling systems, Contact our experts to help.

Air conditioners help to dehumidify the incoming air, but in extremely humid climates or in cases where the air conditioner is oversized, it may not achieve a low humidity. Running a dehumidifier in your air conditioned home will increase your energy use, both for the dehumidifier itself and because the air conditioner will require more energy to cool your house.

TYPES OF CENTRAL AIR CONDITIONERS

A central air conditioner is either a split-system unit or a packaged unit.

In a split-system central air conditioner, an outdoor metal cabinet contains the condenser and compressor, and an indoor cabinet contains the evaporator. In many split-system air conditioners, this indoor cabinet also contains a furnace or the indoor part of a heat pump. The air conditioner’s evaporator coil is installed in the cabinet or main supply duct of this furnace or heat pump. If your home already has a furnace but no air conditioner, a split-system is the most economical central air conditioner to install.

In a packaged central air conditioner, the evaporator, condenser, and compressor are all located in one cabinet, which usually is placed on a roof or on a concrete slab next to the house’s foundation. This type of air conditioner also is used in small commercial buildings. Air supply and return ducts come from indoors through the home’s exterior wall or roof to connect with the packaged air conditioner, which is usually located outdoors. Packaged air conditioners often include electric heating coils or a natural gas furnace. This combination of air conditioner and central heater eliminates the need for a separate furnace indoors.

CHOOSING OR UPGRADING YOUR CENTRAL AIR CONDITIONER

Central air conditioners are more efficient than room air conditioners. In addition, they are out of the way, quiet, and convenient to operate. To save energy and money, you should try to buy an energy-efficient air conditioner and reduce your central air conditioner’s energy use. In an average air-conditioned home, air conditioning consumes more than 2,000 kilowatt-hours of electricity per year, causing power plants to emit about 3,500 pounds of carbon dioxide and 31 pounds of sulfur dioxide.

If you are considering adding central air conditioning to your home, the deciding factor may be the need for ductwork.

If you have an older central air conditioner, you might choose to replace the outdoor compressor with a modern, high-efficiency unit. If you do so, consult a local heating and cooling contractor to assure that the new compressor is properly matched to the indoor unit. However, considering recent changes in refrigerants and air conditioning designs, it might be wiser to replace the entire system.

Today’s best air conditioners use 30% to 50% less energy to produce the same amount of cooling as air conditioners made in the mid 1970s. Even if your air conditioner is only 10 years old, you may save 20% to 40% of your cooling energy costs by replacing it with a newer, more efficient model.

Proper sizing and installation are key elements in determining air conditioner efficiency. Too large a unit will not adequately remove humidity. Too small a unit will not be able to attain a comfortable temperature on the hottest days. Improper unit location, lack of insulation, and improper duct installation can greatly diminish efficiency.

When buying an air conditioner, look for a model with a high efficiency. Central air conditioners are rated according to their seasonal energy efficiency ratio (SEER). SEER indicates the relative amount of energy needed to provide a specific cooling output. Many older systems have SEER ratings of 6 or less. The minimum SEER allowed today is 13. Look for the ENERGY STAR® label for central air conditioners with SEER ratings of 13 or greater, but consider using air conditioning equipment with higher SEER ratings for greater savings.

New residential central air conditioner standards went into effect on January 23, 2006. Air conditioners manufactured after January 26, 2006 must achieve a SEER of 13 or higher. SEER 13 is 30% more efficient than the previous minimum SEER of 10. The standard applies only to appliances manufactured after January 23, 2006. Equipment with a rating less than SEER 13 manufactured before this date may still be sold and installed.

The average homeowner will remain unaffected by this standard change for some time to come. The standards do not require you to change your existing central air conditioning units, and replacement parts and services should still be available for your home’s systems. The “lifespan” of a central air conditioner is about 15 to 20 years. Manufacturers typically continue to support existing equipment by making replacement parts available and honoring maintenance contracts after the new standard goes into effect.

Other features to look for when buying an air conditioner include:

  • A thermal expansion valve and a high-temperature rating (EER) greater than 11.6, for high-efficiency operation when the weather is at its hottest
  • A variable speed air handler for new ventilation systems
  • A unit that operates quietly
  • A fan-only switch, so you can use the unit for nighttime ventilation to substantially reduce air-conditioning costs
  • A filter check light to remind you to check the filter after a predetermined number of operating hours
  • An automatic-delay fan switch to turn off the fan a few minutes after the compressor turns off.

INSTALLATION AND LOCATION OF AIR CONDITIONERS

If your air conditioner is installed correctly, or if major installation problems are found and fixed, it will perform efficiently for years with only minor routine maintenance. However, many air conditioners are not installed correctly. As an unfortunate result, modern energy-efficient air conditioners can perform almost as poorly as older inefficient models.

When installing a new central air conditioning system, be sure that your contractor:

  • Allows adequate indoor space for the installation, maintenance, and repair of the new system, and installs an access door in the furnace or duct to provide a way to clean the evaporator coil
  • Uses a duct-sizing methodology such as the Air Conditioning Contractors of America (ACCA) Manual D
  • Ensures there are enough supply registers to deliver cool air and enough return air registers to carry warm house air back to the air conditioner
  • Installs duct work within the conditioned space, not in the attic, wherever possible
  • Seals all ducts with duct mastic and heavily insulates attic ducts
  • Locates the condensing unit where its noise will not keep you or your neighbors awake at night, if possible
  • Locates the condensing unit where no nearby objects will block airflow to it
  • Verifies that the newly installed air conditioner has the exact refrigerant charge and airflow rate specified by the manufacturer
  • Locates the thermostat away from heat sources, such as windows or supply registers.

If you are replacing an older or failed split system, be sure that the evaporator coil is replaced with a new one that exactly matches the condenser coil in the new condensing unit. (The air conditioner’s efficiency will likely not improve if the existing evaporator coil is left in place; in fact, the old coil could cause the new compressor to fail prematurely.)

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Maintaining Your Air Conditioning System

An air conditioner’s filters, coils, and fins require regular maintenance for the unit to function effectively and efficiently throughout its years of service. Neglecting necessary maintenance ensures a steady decline in air conditioning performance while energy use steadily increases. Click to talk to one of  our home cooling experts for more idea’s on ways to help improve your comfort and the efficiency of your air conditioner.

AIR CONDITIONER FILTERS

The most important maintenance task that will ensure the efficiency of your air conditioner is to routinely replace or clean its filters. Clogged, dirty filters block normal airflow and reduce a system’s efficiency significantly. With normal airflow obstructed, air that bypasses the filter may carry dirt directly into the evaporator coil and impair the coil’s heat-absorbing capacity. Replacing a dirty, clogged filter with a clean one can lower your air conditioner’s energy consumption by 5% to 15%.

For central air conditioners, filters are generally located somewhere along the return duct’s length. Common filter locations are in walls, ceilings, furnaces, or in the air conditioner itself. Room air conditioners have a filter mounted in the grill that faces into the room.

Some types of filters are reusable; others must be replaced. They are available in a variety of types and efficiencies. Clean or replace your air conditioning system’s filter or filters every month or two during the cooling season. Filters may need more frequent attention if the air conditioner is in constant use, is subjected to dusty conditions, or you have fur-bearing pets in the house.

AIR CONDITIONER COILS

The air conditioner’s evaporator coil and condenser coil collect dirt over their months and years of service. A clean filter prevents the evaporator coil from soiling quickly. In time, however, the evaporator coil will still collect dirt. This dirt reduces airflow and insulates the coil, reducing its ability to absorb heat. To avoid this problem, check your evaporator coil every year and clean it as necessary.

Outdoor condenser coils can also become very dirty if the outdoor environment is dusty or if there is foliage nearby. You can easily see the condenser coil and notice if dirt is collecting on its fins.

You should minimize dirt and debris near the condenser unit. Your dryer vents, falling leaves, and lawn mower are all potential sources of dirt and debris. Cleaning the area around the coil, removing any debris, and trimming foliage back at least 2 feet (0.6 meters) allow for adequate airflow around the condenser.

COIL FINS

The aluminum fins on evaporator and condenser coils are easily bent and can block airflow through the coil. Air conditioning wholesalers sell a tool called a “fin comb” that will comb these fins back into nearly original condition.

CONDENSATE DRAINS

Occasionally pass a stiff wire through the unit’s drain channels. Clogged drain channels prevent a unit from reducing humidity, and the resulting excess moisture may discolor walls or carpet.

WINDOW SEALS FOR ROOM AIR CONDITIONERS

At the start of each cooling season, inspect the seal between the air conditioner and the window frame to ensure it makes contact with the unit’s metal case. Moisture can damage this seal, allowing cool air to escape from your house.

PREPARING FOR WINTER

In the winter, either cover your room air conditioner or remove and store it. Covering the outdoor unit of a central air conditioner will protect the unit from winter weather and debris.

HIRING A PROFESSIONAL

When your air conditioner needs more than regular maintenance, hire a professional service technician. A well-trained technician will find and fix problems in your air conditioning system.

The technician should and we will:

  • Check for correct amount of refrigerant
  • Test for refrigerant leaks using a leak detector
  • Capture any refrigerant that must be evacuated from the system, instead of illegally releasing it to the atmosphere
  • Check for and seal duct leakage in central systems
  • Measure airflow through the evaporator coil
  • Verify the correct electric control sequence and make sure that the heating system and cooling system cannot operate simultaneously
  • Inspect electric terminals, clean and tighten connections, and apply a non-conductive coating if necessary
  • Oil motors and check belts for tightness and wear
  • Check the accuracy of the thermostat.

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