Choosing an air conditioning system and contractor is an important decision. Whether it's for service, maintenance or installation of a new air conditioning system it's a decision you don't take lightly. At Service Network we want to provide you with the most information we can to help you make the right decisions. After all, the safety and comfort of your home and your family are in the hands of the company you choose…
Should I consider replacing or buying new air conditioning for my home?
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.
What size system will I need?
Air conditioners are rated by the number of British Thermal Units (Btu) of heat they can remove per hour. Another common rating term for air conditioning size is the "ton," which is 12,000 Btu per hour.
The size of an air conditioner depends on:
how large your home is and how many windows it has;
how much shade is on your home's windows, walls, and roof;
how much insulation is in your home's ceiling and walls;
how much air leaks into your home from the outside; and
how much heat the occupants and appliances in your home generate.
An air conditioner's efficiency, performance, durability, and initial cost depend on matching its size to the above factors.
Should I just buy the largest size system available?
Buying an oversized air conditioner penalizes you in the following ways:
It costs more to buy a larger air conditioner than you need. The “larger-than-necessary” air conditioner cycles on and off more frequently reducing its efficiency. Frequent cycling makes indoor temperatures fluctuate more and results in a less comfortable environment. Frequent cycling also inhibits moisture removal. In humid climates, removing moisture is essential for acceptable comfort. In addition, this cycling wears out the compressor and electrical parts more rapidly. A larger air conditioner uses more electricity and creates added demands on electrical generation and delivery systems.
What features do I need?
You should expect the unit to have an adjustable thermostat, at least two cooling speeds, two fan speeds and an energy efficient setting, which stops the fan when the unit is not cooling. The unit should have an adjustable vent, which allows you to aim the cool air, and an exhaust vent setting allowing fresh air to be introduced from outside. The filter should be easily accessible for removal and cleaning. You want a manufacturer's warrantee for at least 5 years, with full replacement for at least 1 year.
Some of the newer units have an electrostatic filter available either standard or as an option. This filter will remove extremely small particles from the air. This is a super feature for people with allergies.
How much will it cost to run?
Guess what? Your electricity bill is probably unreadable, I know mine is. Theoretically, you should add the generation cost per kilowatt-hour to the delivery cost per kilowatt-hour to get a true cost. However, many areas charge different rates for different usage and have a surcharge for high usage during summer months. Duh!
An easy way is to divide the total payment by the kilowatt-hours used. Do it for your last bill and for last summer's bill and use the higher of the two numbers. This number is not totally accurate, but it works well. (The number should be about 5-50 cents. If it isn't you probably did the sum wrong.)
Don't forget. The national grid is old and needs work. Nuclear power plants are aging too, and will cost a fortune to replace. Oil powered generation will be effected by high oil prices. You can bet money that conventionally generated power is not going to get cheaper.
How do I calculate the payback?
Start with the EER of your old unit. Subtract 1 from this EER for every 5 years of its age -- more if you never clean it. Use the guide to generate the annual cost for the old unit and for the unit you want to buy. You may have to extrapolate if the figures are beyond the range of your chart. Subtract the two numbers to get the annual savings. Divide the purchase price by the annual savings to get the payback time. If the payback time is lower than the warrantee period, it's like money in the bank. If it is less than double the warrantee period, it is still probably a good buy.
You live near Washington DC which has a cooling season of about 600 hours per year and your adjusted electricity cost is about 25 cents per kilowatt-hour. Replacing a 6000 BTU/Hour 6-EER unit with a 5800 BTU/Hour 11 EER unit will save about $60 a year. If you pay $300 for the new unit then you will get your money back in 5 years.
Which AC should I buy?
You should buy the unit of the correct capacity and type that has the highest EER, if you can afford it. Buying a unit of lower EER that costs less is usually a false economy.
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