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1. How a Central A/C works
Central air conditioning helps keep your home cool and reduces humidity levels. By transferring heat from air located inside your home to the outside, conditioned and cooled air is left to be re-circulated. Using electricity as its power source, the compressor inside an air conditioning unit pumps coolant, or refrigerant, back and forth to gather heat and moisture from indoors. Warm air from inside is blown over the cooling coil, which is connected to the compressor, and then pumped back into your home.
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2. Why Do I Need a Load Calculation?
When purchasing a new system, it’s very important that a licensed dealer visit your home to perform a complete evaluation, or “load calculation.” By doing this, he will look at all the factors that affect the heat gain and loss of your home.
The dealer will take into account the climate you live in, as well as the size, shape, and orientation of your home; it’s not enough to merely calculate square footage, although he will do that, too. What type of insulation and how much you have is important along with window size, type, quantity, and the directions they face. He might measure walls and floors; he’ll see what materials the house is made of. He'll check seals, estimate air leakage, and locate existing vents and ductwork.
By combining these and other factors, the dealer will evaluate what size unit your home requires. However, if you are replacing an existing system, you can give your dealer a starting point. You can provide to him the model and serial numbers of your existing units, found on the rating plate.
But you will still require a load calculation. An over or under sized unit is one of the most common problems with any system; when a licensed dealer performs a load calculation, you will have a more efficient system and a more comfortable home.
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3. Which air conditioners are energy efficient?
Much like automobile manufacturers, today’s air conditioner manufacturers are required by law to evaluate and rate their equipment according to its energy efficiency. This rating is known in the industry as a SEER, or Seasonal Energy Efficiency Rating. The higher the SEER, the more efficient the equipment.
Most new homes with central air come equipped with a standard builder’s model. However, when replacement becomes necessary, property owners can upgrade their air conditioning by specifying a more energy-efficient system.
The Ruud Classic XIV® High Efficiency model, for example, has a SEER of 14.00, among the highest available. It’s significantly higher than today’s standard models, many of which carry SEER’s of around 6 to 10.
High SEER models are generally more expensive, but can easily make up the difference by reducing your home energy bills over the long run.
The new standard in the US is 13 Seer. |
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4. EPA's Acceptable Freon Substitutes in Household and Light Commercial Air Conditioning.
Substitutes are reviewed on the basis of ozone depletion potential, global warming potential, toxicity, flammability, and exposure potential. Lists of acceptable and unacceptable substitutes are updated several times each year.
Visit EPA here for more information.
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Acceptable Substitutes for CFCs (class I ODS) in Household & Light Commercial AC
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Evaporative/Desiccant Cooling |
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all CFCs |
N |
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R-407C |
Suva 407C, Klea 407C |
502 |
R, N |
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R-422C |
ICOR XLT1 |
502 |
R, N |
Key: R = Retrofit Uses, N = New Uses
Acceptable Substitutes for HCFCs (class II ODS) in Household & Light Commercial AC
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HFC-134a |
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22 |
N |
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THR-03 |
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22 |
N
NOTE: this determination applies ONLY to window-unit residential air conditioning, and not to central air conditioning systems. |
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ISCEON 59, NU-22, R-417A |
Isceon 59, NU-22 |
22 |
R, N |
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R-410A, R-410B |
AZ-20, Suva 9100, Puron |
22 |
N |
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R-407C |
Suva 9000, Klea 66 |
22 |
R, N |
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R-507, R-507A |
AZ-50 |
22 |
R, N |
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NU-22 |
NU-22 |
22 |
R, N |
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Ammonia Absorption |
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22 |
N |
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Evaporative/Desiccant Cooling |
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all HCFCs |
N |
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R-404A |
HP62 |
22 |
R, N |
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R-125/134a/600a (28.1/70.0/1.9) |
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22 |
R, N |
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RS-44 |
RS-44 |
22 |
R, N |
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R-421A |
Choice R421A |
22 |
R, N |
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R-422D |
ISCEON MO29 |
22 |
R, N |
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R-424A |
RS-44 |
22 |
R, N |
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R-125/290/134a/600a (55.0/1.0/42.5/1.5) |
ICOR AT-22 |
22 |
R, N |
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R-422C |
ICOR XLT1 |
22 |
R, N |
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R-422B |
ICOR XAC1 |
22 |
R, N |
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KDD5 |
KDD5 |
22 |
R, N |
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RS-45 (ASHRAE proposed designation: R-434A) |
RS-45 |
22 |
R, N |
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R-125/290/134a/600a (55.0/1.0/42.5/1.5) |
ICOR AT-22 |
22 |
R, N |
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R-422B |
XAC1, NU-22B |
22 |
R, N |
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R-422C |
XLT1 |
22, 402A, 402B, 408A |
R, N |
Key: R = Retrofit Uses, N = New Uses
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