- How efficient is my air conditioner and how efficient should a new air conditioner be?
- First of all make your building structure efficient.
If your attic has less than 4 inches of insulation then you need more.
- Almost all houses have air leakage from the attic and the crawlspace (if you have one). Find a local contractor who has a blower door to test leakage and make sure they seal the leaks between the attic and the house.
- Close the drapes on your windows during the day.
- It is very likely that your air ducts are leaky.
- Air conditioners – even those with preventative maintenance contracts are likely to have problems – a new higher level diagnosis is required to ensure that the air conditioner is efficient - not just blowing cold air. The biggest common problems are insufficient airflow through the blower and the wrong amount of refrigerant in your air conditioner. You can increase the indoor airflow by avoiding the so called “high efficiency” pleated filters. A regular washable or low cost filter is fine. See Filtration and Allergies.
- If you live in a dry climate a dry climate Western Cooling ControlTM will help.
- If it cools off where you live at night open all the windows or install a whole house fan.
Filtration is the last item on this list. First you should reduce the sources of pollution and reduce where the pollutants can be stored.
- Carpets and fabric covered furniture provide storage for dust of all sizes. Walking on carpet or vacuuming stirs up an invisible cloud of particles around you.
- Of the 21.8 million people reported to have asthma in the U.S., approximately 4.6 (2.7-6.3) million cases are estimated to be attributable to dampness and mold exposure in the home. Mold grows in houses that have too much humidity. The moisture in a home comes from roof, wall, and plumbing leaks, lots of cooking, many people in the house, as well as from outside moisture – rain, irrigation, and high outdoor humidity.
- Fix roof, wall and plumbing leaks right away and make sure water runs away from your house rather than into it.
- Reduce the amount of moist outdoor air from coming into your house. Find a local contractor who has a blower door to test leakage and make sure they seal leaks from the attic down into the house (or up into the house from the crawlspace).
- In moist climates it is unlikely that you will be able to control indoor humidity with a standard air conditioner. Add a dehumidifier and monitor the indoor humidity.
- Always use the bath fan to remove moisture from showering or bathing. Better yet use a quiet high efficiency fan with a humidity sensing switch to turn on the bath fan whenever the humidity is high.
You have heard of dust mites. Approximately 80% of allergy sufferers are allergic to the products of dust mites.
- Wash the sheets and pillow cases in HOT water and hang them outside to dry in the sun.
- High humidity promotes increases in the dust mite population. Reduce indoor humidity as noted in the bullet point directly above.
Needless to say smoke is a real problem, any smoke including tobacco and wood smoke. Have people refrain from smoking in the house, building, or car.
Combustion appliances such as cooking ranges, ovens, and unvented “decorative logs” are sources of pollutants including excess moisture, nitrogen dioxide, and potentially carbon monoxide as well as particulates.
- Don’t use any kind of unvented space or “decorative” heater no matter what!
- Even electric ranges produce pollutants from the burnt food on the elements. Inductive range tops may be a good solution.
- The vent hoods over ranges, if they are vented to outside are helpful – But only if you use them.
- Under no circumstance use an ion generating air filter. These products produce ozone which is a trigger for asthma and is a toxic gas.
- It is controversial whether or not filters in your heating or cooling system will do much good with respect to allergies and Asthma. One reason is the invisible dust cloud that moves with you as you disturb your surroundings. Here are a few things we do know:
- Stand alone HEPA filters can effectively reduce the number of particulates in the room air.
- High MERV filters (MERV 13) on your air conditioner or forced air heater can also reduce particulates, but running your forced air fan all the time is very expensive. High MERV filters are detrimental to the efficiency of your air conditioner unless you use a very large filter (see Airflow Table) AND a 4 inch deep pleated filter. These filters will not fit your standard 1 inch deep filter location and they have to be much larger. You can get a contractor to put in additional filter boxes and run additional ducting to keep your air conditioner efficient.
Well it looks strange, but adding a diffuser cone to your outdoor unit will quiet your air conditioner and increase its efficiency. You can build one to fit your own air conditioner; here is a step by step tutorial, along with a simple spreadsheet for your individual measurements.
4. Do I need a new Air Conditioner?
The cooling delivered and the efficiency of your air conditioner should not decrease over time unless the outside coil suffers from corrosion or the inside coil gets really dirty. So an air conditioner that is 7 years old should be just as good as it ever was as long as it has the right amount of pure refrigerant in it. The Federal minimum standard became SEER 10 in 1992 and changed to SEER 13 in 2006. So if you have a unit built after 2006 there is little reason to change it based on economics.
When you buy an air conditioner make sure:
- You have a contractor test the duct leakage and seal the ducts using mastic (NOT DUCT TAPE). That may very well save more money than replacing the air conditioner.
- You have the contractor replace both the outside unit AND the inside coil (called the evaporator coil). If you don’t do that you will not get the efficiency you were promised.
- You ask the contractor how many microns they evacuate to. Their answer should be 500 microns or less. (Microns are a measurement of pressures near an absolute vacuum.) If they don’t evacuate to 500 microns or less or make an excuse as to why they don’t – get a quality contractor.
If your air conditioner was made before 2006 look at the answer to the next question.
Your old air conditioner can be tested for efficiency by a certified CheckMe!® technician. First they will diagnose your AC for problems, fix them if possible and determine the operating efficiency.
Looking at our database of half a million field tests, the operating efficiencies are usually about 2/3 of their rating.
The best air conditioner to buy depends on why you are buying it:
- Do you want to decrease your Carbon footprint and substantially lower your summer cooling bills? If so a two speed higher efficiency air conditioner (higher than SEER 16) would be your best choice. You should even consider variable speed mini-split air conditioners.
- Do you need to replace a unit that stopped working and your budget cannot cover a high efficiency unit? Then a unit with an SEER of 14 and an EER of at least 12, would be the choice. (See SEER and EER Explained) If your furnace is fine, regardless of its age you don’t need to replace it. However you should consider upgrading to a new high efficiency fan motor.
The average duct leakage in the United States is 25%. That means the average owner is losing 25% of the heating and cooling they paid for. Duct systems should be tested for leakage and sealed with mastic (not duct tape). For more information see Ducts in the Research Section.
Cleaning ducts is not usually effective in changing indoor air quality. If you are concerned with allergies or asthma you should follow the recommendations under Should I filter for allergies and asthma? above.
CheckMe!® is a quality assurance system for diagnosis and repair of residential and commercial heating and cooling systems. CheckMe!® includes training the technicians, using computerized expert systems for diagnosis, and follow up with the customers and technicians to get the job done right the first time.
Here is where you find out if there is a CheckMe!® program in your area