AIR CONDITIONING UNDERSTANDING ENERGY-EFFICIENT AIR CONDITIONING
Do you intend to purchase a new air conditioner? Or, are you unhappy with the way your existing air conditioner works? Are you unsure if you should repair it or replace it? Are you worried about paying hefty utility bills in the summer? This book can assist you if you said “yes” to any of these. It can help you select a new air conditioner, employ professional air conditioning services, learn about different types of air conditioning systems, maintain your air conditioner, and make sure your new air conditioner is installed correctly. The key to cost-effective operation and reducing overall expenses is proper sizing, selection, installation, maintenance, and use.
A technical description of a system’s operation
The essential components and operating principles used by your home refrigerator are also used by air conditioners. The evaporator, a chilly inside coil used by air conditioners to cool homes, does this. The gathered heat is released outdoors by the condenser, a hot outside coil. The serpentine tubing of the evaporator and condenser coils is encircled by metal fins. Typically, copper is used to make this tubing. A heat transfer fluid, also known as refrigerant, is moved between the evaporator and the condenser by a pump known as the compressor. The refrigerant is compelled by the pump through the coils’ circuit of tubing and fins. In the indoor evaporator coil, the liquid refrigerant evaporates, removing heat from the indoor air and cooling the house. The warm refrigerant gas is piped outside into the condenser, where it cools and transforms back into a liquid, releasing its heat to the air passing over the metal fins and tubing of the condenser.
Air conditioner types
Room air conditioners, split-system central air conditioners, and packaged central air conditioners are the three basic types of air conditioners.
A/C Units for Rooms
Room air conditioners chill individual rooms as opposed to the whole house. Despite having a generally lower efficiency than central air conditioners, room air conditioners are less expensive to run if they simply deliver cooling where it is needed.
Smaller room air conditioners (those using less than 7.5 amps of power) can be connected to any 15- or 20-amp, 115-volt home circuit that is not being used by any other large appliances. Larger room air conditioners, particularly those that consume more than 7.5 amps, require a separate 115-volt circuit. Larger models need their own 230-volt circuit.
COOLING UNITS IN THE CENTER
Cool air is circulated by central air conditioners using a network of supply and return ducts. Cooled air from the air conditioner enters the house through supply ducts and registers, which are apertures in the walls, floors, or ceilings that are protected by grills. As it moves throughout the house, this cooled air warms up, and through return ducts and registers, it returns to the central air conditioner. Either a split-system unit or a packaged unit makes up a central air conditioner.
An inside cabinet houses the evaporator in a split-system central air conditioner, while the condenser and compressor are housed outside in a metal cabinet. This internal cabinet is where the furnace or the indoor portion of a heat pump is located in many split-system air conditioners. The primary supply duct or cabinet of this furnace or heat pump houses the evaporator coil for the air conditioner. The most affordable central air conditioner to install is a split-system if your home currently has a furnace but no air conditioner.
Evaporator, condenser, and compressor are all housed in one cabinet that is often mounted on a roof or a concrete slab close to the home’s foundation in a packaged central air conditioner. Small business buildings also employ this sort of air conditioner. Air supply and return ducts link to the packaged air conditioner, which is often outside, through the outside wall or roof of the house. A natural gas furnace or electric heating coils are frequently included in packaged air conditioners. There is no longer a need for an inside furnace thanks to this system’s central air conditioner and heater.
In hot, dry conditions, an evaporative cooler, sometimes known as a “swamp cooler,” is an entirely different kind of air conditioner that is effective.
Similar to the way that perspiration evaporates to cool your body on a hot (but not extremely humid) day, these devices cool external air via evaporation and blow it into the building. Windows are partially opened when using an evaporative cooler to let heated indoor air out while it is being replenished by cooled air.
Evaporative coolers consume about a fifth the energy of central air conditioners and install for about half the price. They are only appropriate for low-humidity environments, and they require more frequent maintenance than refrigerated air conditioners.
UPDATING CURRENT AIR CONDITIONERS
Older air conditioners might still be able to function rather efficiently for years. You must, however, carry out regular operation and maintenance if you want your older air conditioner to last.
PROBLEMS WITH THE A/C
The incorrect operation of an air conditioner is one of the most frequent issues. Close all of your home’s windows and outside doors if your air conditioner is on. Other frequent issues with current air conditioners are caused by improper installation, subpar service methods, and insufficient maintenance. Your air conditioner’s installation could have led to leaking ductwork and insufficient airflow.
The amount of refrigerant in the system, or the refrigerant charge, frequently deviates from the manufacturer’s recommendations. The performance and efficiency of the unit are compromised if the necessary refrigerant charge is not done during installation. By adding refrigerant to a system that is already full, service workers frequently miss refrigerant charging issues or even make them worse. Manufacturers of air conditioners typically produce tough, superior goods. If your air conditioner breaks down, it typically happens for one of the typical causes stated below:
If the refrigerant in your air conditioner is low, either it was installed improperly or it has leaks. Simply adding more refrigerant won’t fix a leak. Any leaks should be fixed, the repair should be tested, and then the system should be charged with the appropriate amount of refrigerant. Keep in mind that your air conditioner will operate at its best performance and efficiency when the refrigerant charge precisely fits the manufacturer’s specification and is neither undercharged nor overcharged.
The air conditioner won’t function properly, and the compressor or fans are likely to break early if you let the filters and cooling coils get unclean.
DEFECTIVE ELECTRIC CONTROL
When an enormous system runs the air conditioner repeatedly, as is usual, the compressor and fan controls might become worn out. Electrical connections and contacts should be examined during a professional service call because corrosion of wire and terminals, a concern in many systems, should also be addressed.
For an air conditioner to operate successfully and efficiently over the course of its useful life, frequent maintenance is required for the unit’s filters, coils, and fins. When proper maintenance is neglected, the performance of the air conditioner will gradually deteriorate while energy consumption will gradually rise.
FILTERS FOR AIR CONDITIONERS
Replace or clean your air conditioner’s filters on a regular basis to maintain the efficiency of your air conditioner, which is the most crucial maintenance task. Filters that are clogged or unclean obstruct normal airflow and dramatically lower a system’s efficiency. When the regular airflow is blocked, dirt may be carried into the evaporator coil by air that bypasses the filter, reducing the coil’s ability to absorb heat. Somewhere along the return duct’s length are filters. Filters are frequently found in furnaces, walls, ceilings, and air conditioners.
Some filter types can be reused, while others need to be changed. They come in many different varieties and efficiency. Every month or two throughout the cooling season, clean or replace the filter(s) in your air conditioning system. If the air conditioner is used frequently, is exposed to dusty circumstances, or you have furry pets in the house, filters may require more frequent care.
COILS FOR AIR CONDITIONERS
Over the course of their months and years of use, the evaporator coil and condenser coil of the air conditioner accumulate dirt. The evaporator coil doesn’t get dirty as quickly with a clean filter. The evaporator coil will eventually continue to gather dirt, though. By insulating the coil and reducing airflow, this dirt lowers the coil’s capacity to absorb heat. As a result, you should inspect and clean your evaporator coil once a year.
If the surrounding area is dusty or there is vegetation, outdoor condenser coils can also get very dirty. The condenser coil is clearly visible, so you can tell if debris is accumulating on its fins.
Debris and dirt should be kept to a minimum close to the condenser. Dirt and debris may come from your lawnmower, dryer vents, or falling leaves. To ensure enough airflow around the condenser, clean the space around it, clear away any debris, and cut back any vegetation by at least two feet.
Evaporator and condenser coils’ aluminum fins are brittle and can bend easily, preventing airflow through the coil. These fins can be combed back to nearly their former condition using a product that air conditioning wholesalers sell under the name “fin comb.”
Sealing and insulating air ducts prevents the loss of chilled air from supply ducts or the entry of heated attic air into return ducts, which both result in significant energy losses. According to recent studies, between 10% and 30% of the conditioned air in a typical central air conditioning system escapes through the ducts.
Ducts must be airtight for central air conditioning to function effectively. Since leaky ducts may be hard to spot without experience and test equipment, hiring a qualified professional service specialist to identify and fix them is a wise investment. Duct “mastic” is required to seal ducts. For sealing ducts, the tried-and-true method of duct tape frequently fails.
A duct system’s efficiency can be affected by obstructions almost as much as by leaks. A supply or return register should not have furniture, draperies, or tightly fitting interior doors blocking the airflow. Significant airflow barriers can also include blocked evaporator coils and dirty filters.
Heat conduction in ducts is an issue that is almost as severe as air leakage and obstructions because of the significant temperature difference between attics and ducts. Attic ducts should be made airtight as well as substantially insulated.
A NEW AIR CONDITIONER FOR YOUR HOME TO PURCHASE
When compared to air conditioners constructed in the middle of the 1970s, the finest models now consume 30 to 50 percent less energy to deliver the same level of cooling. Even if your air conditioner is only ten years old, switching to a more recent, more efficient model could help you save 20 to 40 percent of your cooling energy bills.
YOUR AIR CONDITIONERS’ SIZE
British Thermal Units (Btu) are used to measure how much heat an air conditioner can remove in an hour. The “ton,” which is 12,000 Btu per hour, is another frequent rating term for the size of an air conditioner.
WHAT SIZE AIR CONDITIONER SHOULD YOU USE?
An air conditioner’s size is determined by:
How big and how many windows your home has, how much shade it gets on its windows, walls, and roof, how much insulation it has in its ceiling and walls, how much air it lets in from the outside, and how much heat its residents and appliances produce.
Matching an air conditioner’s size to the aforementioned parameters will affect its effectiveness, performance, longevity, and initial cost.
Make sure the air conditioner you purchase is the appropriate size. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and the Air Conditioning Contractors of America (ACCA) both publish calculating methods for sizing central air conditioners. To size your new central air conditioner, reputable air conditioning contractors will utilize one of these techniques, frequently carried out with the use of a computer.
Recognize that a big air conditioner won’t offer the optimum cooling. You pay a price for purchasing a large air conditioner in the following ways.
A larger air conditioner than you require will cost more. The larger air conditioner runs less efficiently since it cycles on and off more frequently. Frequent cycling causes indoor temperatures to vary more, which makes the atmosphere less comfortable. Additionally, frequent cycling prevents moisture removal. Removing moisture is crucial for appropriate comfort in humid regions. Additionally, this cycling quickly degrades the electrical components and the compressor. A larger air conditioner consumes more electricity and puts more strain on the infrastructure for generating and delivering electricity.
EFFICIENCY OF AIR CONDITIONERS
An energy-efficiency rating for each air conditioner indicates how many Btu per hour are eliminated for every watt of power it consumes. The Energy Efficiency Ratio, or EER, is the efficiency rating used for room air conditioners. It is the Seasonal Energy Efficiency Ratio, or SEER, for central air conditioners. All new air conditioners are required to have an Energy Guide Label prominently attached, which lists these ratings. Many air conditioner manufacturers take part in the EnergyStar® labeling program, which is voluntary (see Source List in this publication). Appliances with the EnergyStar® badge have good SEER and EER ratings.
New air conditioners with greater SEERs or EERs typically cost more money. An energy-efficient model’s higher upfront cost will, however, be more than offset by its long lifespan. By waiving part or all of the price difference, your utility company may encourage the purchase of a more energy-efficient air conditioner. Purchase the most energy-efficient air conditioner you can afford, especially if you frequently use (or anticipate using) one and/or if your electricity costs are high.
ROOM AIR CONDITIONERS—EER—The typical range for room air conditioners is between 5,500 and 14,000 Btu per hour. Room air conditioners constructed after January 1, 1990, must meet national appliance requirements and have an EER of 8.0 or above. If you reside in a mild environment, get a room air conditioner with an EER of at least 9.0. Choose one with an EER of greater than 10 if you reside in a hot climate.
According to the Association of Home Appliance Manufacturers, between 1972 and 1991, the average EER of room air conditioners increased by 47%. Your air conditioning energy costs will be lowered in half if you replace a room air conditioner from the 1970s with a modern one that has an EER of 10.
SEER-CENTRAL AIR CONDITIONERS
SEER ratings of 9.7 and 13.0 are required by national minimum standards for single-package and split systems, respectively. However, there is a large selection of units with SEERs of 18, so you are not forced to choose the bare minimum.
Prior to 1979, central air conditioners had SEER ratings that ranged from 4.5 to 8.0. Your air conditioning costs will be reduced by more than half if you replace a central air conditioner from the 1970s with a unit that has a SEER of 13 instead of one with a SEER of 6.
Due to the placement of the unit or its proximity to your neighbor’s window, the outside section’s sound level may be significant to you. The majority of modern devices have sound ratings that are expressed in decibels.
QUALIFICATIONS OF PROFESSIONAL SERVICE
Hire a qualified service expert when your air conditioner requires more than the routine maintenance already described. A skilled technician will identify and address issues with your air conditioning system. But not every service technician is skilled. Inept service technicians skip a complete diagnosis and merely apply the bare minimum band-aid fixes.
REQUIRE THE TECHNICIAN TO: Verify the correct amount of refrigerant; utilize a leak detector to test for refrigerant leaks;
instead of releasing refrigerant into the atmosphere unlawfully, catch any refrigerant that needs to be removed from the system;
In any area of your system that operates in the attic, crawl space, or garage, check for and seal any duct leakage.
determine the evaporator coil’s airflow;
ensure that the electric control sequence is proper and that the heating and cooling systems cannot function at the same time;
inspecting electrical terminals, sanitizing and tightening connections, and, if required, using a non-conductive coating;
Oil motors, inspect belts for wear and tightness, and confirm the thermostat’s accuracy.
CHOOSING A CONTRACTOR
The most crucial and challenging step in purchasing a new central air conditioning system may be selecting a contractor. Request recent references from potential contractors. Inform your contractor of the aspects of the former system that you liked and disliked if you are replacing your central air conditioner. Ask the contractor to investigate the system’s failure if it occurred. When a new system is being implemented, faults can be fixed most effectively.
The contractor you select should consider these factors when developing your new air conditioning system:
Use a written calculation process or computer program to size the air conditioner. Provide a written contract outlining the key components of your installation, including the findings of the cooling load calculation.
Keep pricing out of your decision-making process. Your top focus should be the installation’s quality because it will affect comfort, durability, and energy costs.
AIR CONDITIONER INSTALLATION AND SITE
Your air conditioner will operate effectively for years with only modest routine maintenance if it is installed correctly or if significant installation issues are discovered and remedied. Many air conditioners, though, are not installed properly. Unfortunately, as a result, more energy-efficient air conditioners can have performance that is practically on par with older inefficient units.
When installing a new central air conditioning system, make sure your contractor follows these steps:
enables sufficient inside area for the new system’s installation, upkeep, and repairs. It also adds an access door to the furnace or duct to make it possible to clean the evaporator coil.
ensuring there are adequate supply registers to distribute cool air and enough return air registers to convey heated home air back to the air conditioner by using a duct-sizing methods like the Air Conditioning Contractors of America (ACCA) Manual D.
wherever practical, place ductwork inside the conditioned space rather than in the attic, and insulate it when it must be run outside the treated structure.
duct mastic is used to seal all ducts, and attic ducts are substantially insulated.
place the condensing unit, if possible, so that its loudness won’t keep you or your neighbors up at night.
If at all feasible, locate the condensing unit in a shaded area to cut your air conditioning expenditures by 1% to 2%.
confirms that the air-flow rate and refrigerant charge of the recently installed air conditioner are exactly as the manufacturer specified.
Place the thermostat far from heat sources, such as supply registers or windows.
Make sure the evaporator coil is replaced with a new one that precisely matches the condenser coil in the new condensing unit if you are replacing an older or failed split system. The efficiency of the air conditioner won’t likely increase if the old evaporator coil is kept in place; in fact, the old coil might cause the new compressor to break down too soon.
When setting up a new room air conditioner, make an effort to:
Place the air conditioner near the middle of the room, against a wall, and on the house’s shadiest side.
Reduce air leakage by firmly securing the room air conditioner into the opening and caulking cracks with foam weatherstripping.
You can save money and lower pollution by keeping an eye on your air conditioning system. Keep an eye on how well your current system is functioning and perform routine maintenance on it. Alternatively, if you need to buy a new air conditioner, make sure it is properly fitted, sized, and rated for EER or SEER.
YOUR AIR CONDITIONER IN USE
An air conditioner will cool the air in your home rather rapidly unless your contractor has sized it to enhance humidity control rather than just lowering the temperature. Only turn it on when your home is occupied for efficient operation. A programmable thermostat is something you might want to install. On a hot day, you can use these to program the air conditioner to start before you get home from work. For the fact sheet on automatic and programmable thermostats, get in touch with EREC (see Source List). Keep the drapes or blinds drawn on the windows that face east, south, and west during the day. Your home’s solar heat gain will be decreased as a result.