The job of your home air conditioner is move heat from inside your home to the outside, thereby cooling you and your home. Air conditioners blow cool air into your home by pulling the heat out of that air. The air is cooled by blowing it over a set of cold pipes called an evaporator coil. This works just like the cooling that happens when water evaporates from your skin. The evaporator coil is filled with a special liquid called a refrigerant, which changes from a liquid to a gas as it absorbs heat from the air. The refrigerant is pumped outside the house to another coil where it gives up its heat and changes back into a liquid. This outside coil is called the condenser because the refrigerant is condensing from a gas back to a fluid just like moisture on a cold window. A pump, called a compressor, is used to move the refrigerant between the two coils and to change the pressure of the refrigerant so that all the refrigerant evaporates or condenses in the appropriate coils.
Dolang contains other products and information you need, so please check it out.
The energy to do all of this is used by the motor that runs the compressor. The entire system will normally give about three times the cooling energy that the compressor uses. This odd fact happens because the changing of refrigerant from a liquid to a gas and back again lets the system move much more energy than the compressor uses.
Before refrigeration air conditioning was invented, cooling was done by saving big blocks of ice. When cooling machines started to get used, they rated their capacity by the equivalent amount of ice melted in a day, which is where the term “ton” came from sizing air conditioning.
A ton of cooling is now defined as delivering 12,000 BTU/hour of cooling. BTU is short for British Thermal Unit (and is a unit that the British do not use) The BTU is a unit of heating - or in this case, cooling - energy. It’s more important, however, to keep in perspective that a window air conditioner is usually less than one ton. A small home central air conditioner would be about two tons and a large one about five tons.
Unlike most furnaces, air conditioners are complex mechanical systems that depend on a wide variety of conditions to work correctly. They are sized to meet a certain “load” on the house. They are designed to have certain amount of refrigerant, known as the “charge”. They are designed to have a certain amount of air flow across the coils. When any of these things changes, the system will have problems.
If you produce more heat indoors either from having more people or appliances or because of changes in the house, the air conditioning may not be able to keep up.
If the refrigerant charge on the system leaks out, it lowers the capacity of the system. You will simply get less cooling and system will not be able to keep up when the load gets high.
If airflow across the outdoor (condenser) coil is reduced, the ability to reject heat outdoors is reduced and the again the capacity of the system may go down, especially at higher outdoor temperatures.<
In dry climates such as the Southwest United States, the same issues happen with regard to the indoor (evaporator) coil: higher airflow helps, lower airflow hurts. In humid climates, the situation is more complex. At higher airflows, there will be less dehumidification, leading to high indoor humidities. If the airflow gets too low, however, the evaporator coil may freeze. This makes performance worse and can damage the compressor until it fails - leaving you with an expensive repair bill and no cooling!
Almost every air conditioning system has a filter upstream of the evaporator coil. This can be in the return grille or in special slots in the duct system and can be a fuzzy-looking or a folded paper filter. This filter removes particles from the air stream to both keep the air conditioning system clean and to remove particles from the air.
As the filter does its job, it gets loaded with more and more particles. This actually has the effect of making it more efficient, but it also increases resistance and reducing airflow. When this happens, it is time to change the filter. How long it will take to happen depends on how dirty the air is and how big the filter is.
If you don’t change the filter, the air flow will go down, and the system will not perform well. Not only that, but if the filter is too dirty, it starts to become a source or air pollution itself.
If you take the filter out completely, you would solve the low air flow problem, but this victory would be short lived. The particles that the filter would have taken out will now build up on your evaporator coil and eventually cause it to fail. A new filter is a lot cheaper.
When you do buy a new filter, ASHRAE recommends getting one with a Minimum Efficiency Rating Value of MERV 6 or higher.
Routine maintenance such as changing filters can be handled by most consumers, but others require professional service.
It’s a good idea to brush dirt and obstructions from the coils and the drains at the start of each cooling season. Depending on the system and the consumer, this may require a service call from a professional.
If the system is not producing as much cold air as is normal, it could also be an indication of a refrigerant charge or airflow problems. These problems may require servicing.
Another reason systems may appear not to be producing enough cold air is because of duct leakage. Duct leakage can sap 20 to 40% of the energy out of even a well-operating air conditioner, if the ducts pass outside the cooled space (this includes attics, crawlspaces and garages). Ducts outside need to be well insulated. Various products exist specifically for insulating ducts that can be installed by a keen home owner or a professional contractor.
You might be able to get an extra half ton of air conditioner capacity for free, if you seal your leaky ducts. If the ducts are accessible, handy consumers can seal ducts with mastic—that white sticky stuff you can paint on the ducts. Otherwise you would need a professional to seal the ducts.
Sealing leaky ducts may be the biggest single thing you can do to improve efficiency, but a lot of the issues mentioned above will help as well: replace dirty filters, keep the right charge and airflow, clean the coils.
Another thing to do is to make sure the outdoor (condenser) unit is not so hidden from sight that its air flow is blocked or that leaves or other matter are not clogging it.
If you are replacing the air conditioner, look to buy high efficiency equipment. The most generally known efficiency rating is Seasonal Energy Efficiency Rating (SEER). SEER 13 is the minimum efficiency you should consider, but higher efficiencies are likely to be quite cost effective.
Depending on your climate, you may wish to consider other efficiency numbers as well. For example, in hot, dry climates you should look at the Energy Efficiency Rating (EER) which says how well the system will work at peak conditions. If you live in a hot, humid climate you need to consider how well the unit can dehumidify.<
You can make your air conditioner work better by reducing the size of the job it has to do. You can do this by improving the building or reducing the internally generated loads that your air conditioner must deal with.
Improving the building “envelope” includes things such increasing insulation levels or shading windows or reducing air leakage. Such improvements will reduce energy spent on heating and cooling, but may require substantial time or investment. When putting in a new roof or new windows, it is usually cost effective to use high-efficiency products. “Cool” roofing, for example, can save half a ton of cooling and a lot of energy over the year.
Reducing internal loads can be simpler. Shut off unneeded electrical appliances, lights and equipment. Shift appliance use (such as washers and dryers) to cooler times of the day. Use local exhaust fans to remove heat and humidity from kitchens and baths. Buying Energy Star or similarly efficiency appliances helps as well.
In some climates other techniques can be used to reduce the load on the air conditioner. In dry climates evaporative air conditions (the modern version of what used to be called “swamp coolers”) can provide substantial cooling. In climates with large temperature swings, such as the hot, dry climates, you can reduce the load by bringing in large amounts of cool outdoor air. Such systems can be called “night cooling” “ventilative cooling” or “residential economizers”.
The previous points have focused on cooling, but the original definition of air conditioning contains more than that; an ideal air conditioner should heat, cool, clean, ventilate, humidify and dehumidify as needed to provide health and comfort. In fact the second most important objective of the original definition is to provide ventilation. Whether or not the piece of equipment we call an air conditioner provides it, ventilation is needed.
Without adequate ventilation, contaminants generated indoors will can lead to significant health and comfort problems. ASHRAE recommends that there be at least enough ventilation to exchange the air inside house once every four hours, depending on house design.
Older homes tend to have leakier walls and leakier ducts and mostly get sufficient ventilation through such leakage. Such leakage and infiltration may not be the most energy efficient approach to ventilation and is an opportunity for savings.
Most new homes and some existing homes are relatively tight and thus require mechanical ventilation to meet minimum ventilation requirements.
Humidity control was the problem that originally spurred the need for air conditioning. Lack of humidity control in hot, humid climates, in particular, can lead to mold growth and other moisture-related problems. High indoor humidities can lead to health and comfort problems.
Modern air conditioners dehumidify as they cool; you can see that by the water that drains away, but this dehumidification is incidental to their main job of controlling temperature. They cannot independently control both temperature and humidity.
In hot, humid climates the incidental dehumidification that occurs may not always be enough to keep the indoor humidity conditions acceptable. (ASHRAE recommends roughly a 60% relative humidity maximum at 78F.) The maximum dehumidification happens not at the hot times of the year—when the air conditioner is running a lot—but at mild times of the year when the air conditioner runs very little.
Want more information on Air Conditioning Trainer? Feel free to contact us.
Although there are some leading edge air conditioning systems that promise to independently control humidity, conventional systems may not be able to sufficiently control the problem and can cause comfort or mold problems in certain situations. Some current high-end systems have enhanced dehumidification, but when the existing system cannot sufficiently dehumidify, it may be necessary to buy a stand-alone dehumidifier.
Do not set your thermostat to the “fan on” position. In this position the fan blows air all the time whether your cooling system is running or not and one key impact is that a lot of the moisture your system just took out of the air, will be blown back into the house before it can drain way.
Use exhaust fans during moisture-producing activities. Cooking, bathing, washing, and similar activities produce a lot of moisture inside the home. Exhaust that moisture directly outdoors using a fan. Similarly, avoid drying clothes indoors except with a clothes dryer that is exhausted directly outdoors.
Do not open windows or use ventilative cooling when it is too humid outside.
These 10 points will help consumers more aware of their air-conditioning systems and better able to care for them and use them well. Should it become necessary to replace that system seek out a qualified HVAC professional, preferably, of course, a member of ASHRAE.
ASHRAE is the world’s foremost technical society in the fields of heating, ventilation, air conditioning and refrigeration. The Society helps keep indoor environments comfortable and productive, deliver healthy food to consumers and preserve the outdoor environment. ASHRAE’s technical foundation is built by some 50,000 volunteer members, including consulting engineers, contractors, manufacturers, manufacturing representatives/sales, and architects.
Central air conditioning
A true central air conditioning system uses ducts to distribute cooled air throughout the house. In a “split system,” the most common design, refrigerant circulates between an indoor coil and a matching—meaning from the same brand—outdoor condenser with compressor (see the illustration below). The refrigerant cools the air, dehumidifying it in the process; a blower circulates air through ducts throughout the house. A thermostat maintains the temperature at the setting you select.
Split ductless systems
Split ductless systems have an outside condenser and compressor, and one to four or more indoor blower units, called air handlers, mounted high on the wall, that distribute air. The indoor and outdoor sections are connected by a thin conduit that houses the power cable, refrigerant tubing, and a condensate drain. The conduit is run through about a 3-inch hole hidden behind each air handler. Each air handler cools the room in which it’s installed, and you set the temperature with a remote control. Professional installation is recommended. While not technically central air, they’re much quieter and more efficient than window ACs or portable ACs and can be an easier, more affordable option to install than a true central air system.
You can also consider an air-source heat pump in place of an AC-only system. Heat pumps can provide both heating and cooling. In cooling mode, they work exactly like air conditioners. And come colder weather, they’re the most energy-efficient system for home heating.
They’ve been common in warm parts of the U.S. for decades, but now there are plenty of air-source heat pumps that can provide most or all of a home’s heating needs, even in cold climates. You can also use a heat pump in combination with an existing or supplementary heating system. An installer can set it up so that the heat pump operates most of the time, but then when the outdoor temperature drops below a certain threshold and the heat pump becomes less practical, another system—such as a gas-fired furnace—will kick in. (A guideline for that threshold is about 20° F, but the cutoff can be a little warmer or much colder depending on the system.)
Heat pumps are available in ducted or ductless versions. (Some so-called ductless air conditioners are actually heat pumps.) They tend to cost a little more than AC-only units but less than the combined cost of a new heating and cooling system. Because heat pumps are so energy-efficient, some state governments offer tax incentives or even direct cash rebates to homeowners who install air-source heat pumps, which sometimes make them the lowest-cost option for home heating and cooling. Read our heat pump buying guide for more.
If you are installing an AC system from scratch, your contractor should calculate the size of the cooling equipment you need using recognized methods, such as those you’ll find in the Residential Load Calculation Manual, aka Manual J, from the Air Conditioning Contractors of America (ACCA).
If your home already has ductwork but you’re installing your first AC system, keep in mind that ducts used for heating might not be the right size or in the right location for optimal cooling. Your contractor should ensure that duct sections are properly sized and that there are enough supply registers to deliver sufficient air to the right spots. Undersized ductwork can lead to inefficient and noisy operation.
Also, it’s wise to make sure your ducts are sealed and insulated. Otherwise, air can escape, wasting 20 to 30 percent of the energy used to run your system. Sealing your ducts will keep you cooler in the summer and warmer in the winter.
Size, aka Capacity
An air conditioner’s size—which is an indicator of its cooling capacity—is measured in British thermal units per hour (Btu/hr.) or in “tons.” One ton of cooling equals 12,000 Btu/hr. For rough sizing guidance, check the Energy Star website. But the best option is to have your contractor do a load calculation based on a recognized method, such as one in Manual J from the ACCA.
It’s important to pick the right AC capacity for the size of your home. A unit that’s too small will struggle to keep your home comfortable. An oversized unit will cost you more to purchase, and (unless it’s a model with a variable-speed compressor) will cycle on and off more often than it should, stressing the components and struggling to control the humidity in your home.
If you’re replacing your central air, you should look into whether you really need the same size system as your old unit or if you can shrink it a bit. Any changes you’ve made to improve your home’s energy efficiency, such as upgrading your windows or adding insulation, can reduce your cooling needs. On the other hand, if you’ve added rooms, you might need more cooling.
Efficiency
This describes how much cooling the unit delivers for each watt of electricity. Efficiency is expressed as the seasonal energy-efficiency rating or SEER. The higher the SEER, the greater the efficiency. Higher-SEER ACs tend to cost more, but they’ll often pay for themselves over time through lower energy costs. The minimum SEER allowed for a new split system central air conditioner in the U.S. today is 14, which is at least 20 percent more efficient than minimum-efficiency models made even 10 years ago. Systems that meet the Energy Star guidelines for efficiency have a minimum SEER of 15. The most efficient models reach a SEER of at least 26.
Noise
According to our reader survey, quiet operation is the feature that’s the best predictor for an owner’s overall satisfaction with their air conditioner. Manufacturers publish the noise levels for their products across a variety of outdoor temperatures and fan speeds, measured in decibels. A lower rating is better, especially if the AC will be installed near a bedroom window.
Reliability
Reliability is the second-best predictor for an owner’s overall satisfaction with an air conditioner (tied with how quickly it cools a room, though that has more to do with whether the AC is sized correctly for your home and whether it’s maintained properly). Consumer Reports rates the predicted reliability of 22 central air conditioner brands, based on data that members have shared about more than 13,000 new AC units they bought and installed in their own homes between and .
Central AC systems need regular maintenance for optimal performance. When arranging your installation, it’s worth negotiating a service plan that combines regular inspections with discounts on repairs and a labor warranty into the overall price. Prices for such a service can vary widely.
Here’s what you’ll want the service technician to handle: Once a year, have them clean and flush the coils, drain the pan and drainage system, and vacuum the blower compartments. The contractor should also check to make sure that the system is properly charged with refrigerant, that there are no leaks, and that all mechanical components are working properly.
You can also handle some of the maintenance on your own. Clean grilles and filters monthly. Clear debris and dirt from condenser coils and check for blockages in the drainpipe. Follow the AC manufacturer’s recommendations for changing the filter as well as the filter manufacturer’s recommendations for how often you should change the filter. In general, the thicker the disposable filter, the less often it needs to be changed. (The HVAC filters we test last between three and 12 months.)
If your HVAC system was installed before , it may rely on the refrigerant Freon, a trademark name for several different refrigerants including chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons such as HCFC-22 (or R-22). These chemicals deplete protective ozone from the atmosphere. The Environmental Protection Agency phased out CFCs in the s and HCFCs in .
The Environmental Protection Agency has since allowed the use of R-410A, another ozone-threatening HCFC refrigerant, but started requiring manufacturers to stop producing units with R-410A in . While manufacturers are still allowed to sell and install any units they created prior to , the industry has largely started migrating to R-454B and R-32. Manufacturers are still allowed to produce individual parts to service systems that use R-410A, but it may be worth shopping around for a central air system that uses the new refrigerants to ensure access to long-term support, maintenance, and safety.
If you still have a system that uses HCFC, you aren’t required to replace it now. It’s only an environmental threat when it leaks, so ask your technician to check for leaks during your annual maintenance visit. Better yet, consider replacing your AC system with a newer one. It will not only be better for the environment but also be more energy-efficient.
Programmable thermostats. Setting your smart or programmable thermostat at the right temperature can reduce your cooling costs by about 10 percent. The right temperature depends on your comfort level, but start by setting it at 78° F and experiment until you find the sweet spot. You’ll save about 3 percent on your utility bill for every degree you raise the set temperature for your central air, according to the Department of Energy. And keep in mind that using a box or ceiling fan, which costs little to run, can make you feel 3° F to 4° F cooler.
Outdoor space. The compressor needs adequate airflow to operate correctly, so make sure to keep at least 2 to 3 feet of space between the unit and any plants or structures. There should also be 5 feet of clearance between the top of the unit and any trees above. You’ll also want to make sure there’s enough space for you or a technician to access and service the unit. And your local building codes might have regulations about how close an outdoor compressor is allowed to be to a neighbor’s window or property line.
Whether you’re replacing an older air conditioner or installing one for the first time, finding a trustworthy contractor to install and service the air conditioning system matters the most. Here’s what to do.
Ask around. Seek referrals from neighbors, family, or business associates. It’s wise to get price quotes from at least three contractors.
Check their background. Contractors who bid on your installation should show you verification of bonding and insurance, plus any required contractor’s licenses. Check with your local Better Business Bureau and consumer affairs office for complaint records. It’s a plus if technicians are certified by a trade organization, such as North American Technician Excellence or HVAC Excellence, to service residential heating and cooling equipment. Those and similar programs assess the technician’s knowledge of specific types of equipment and their proper service methods.
Get specifics. Contractors who bid on your job should calculate the required cooling capacity using a recognized method, such as one found in the ACCA’s Residential Load Calculation Manual, also called Manual J. An additional reference for assessing ductwork needs is Manual D. The calculations produce a detailed, room-by-room analysis of cooling needs. Ask for a printout of all calculations and assumptions, including ductwork design. Be wary of a contractor who bases estimates merely on house size or vague rules.
For more Industry 4 0 Teaching Platform Supplierinformation, please contact us. We will provide professional answers.