Air conditioning is not just a luxury item for many houses anymore. When building a new house it is often included without question. There are so many options when it comes to central air in a house. The air conditioner BTU is a big thing to consider. The efficiency of the air conditioner is also a big factor to look at. Many new home builders will include a builder model AC unit in the price of the house. If the homeowner wants to have a better, higher efficiency unit, they have to pay extra for that. How much extra should they pay and still come out with a good deal?
There are a few things to check out when upgrading the air conditioning unit. When buying the higher efficiency model it will usually include things like high and low pressure cutout switches in the outdoor condenser unit. This can be very valuable and save the compressor from going bad if there is a problem.
That could be worth the extra cost right there. Also with a higher efficiency unit, the indoor air handler will include a higher efficiency blower motor. The ECM motors will run much more efficient then a regular motor. The efficiency is even greater if the motor is run at low speeds much of the time.
The most confusing issue with any air conditioning is the SEER rating that the US Government uses to rate air conditioning units. The simplest formula I can use to explain this is that the SEER rating compares the cooling BTU's that are made by the unit per unit (KW) of electricity used. Usually expressed as BTU's/Kilowatt of electric. Of course the more BTU's produce per kilowatt of electric consumed the better off you are.
To arrive at a usage number you would have to figure up the number of hours per year that you may be running the air conditioning unit. That can be done by taking the degree day information provided by the weather service for your area and through some fairly complex formula's coming up with usage for your house. I suggest that it may be much easier to just figure how many days you will be running the air conditioner and how many hours a day it might actually run. The specifications provided by the manufacturer of the unit you will use show the electrical usage of the unit. Take the watts per hour consumed by the unit, times the hours run time, divide by 1000 and you will have the kilowatt hour of electric that the unit will consume. Now take that and times it by the number of days a year the unit will run. Then figure that times the cost of the electric per kilowatt hour from your electric company.
If with these numbers you find that your pay back will be five years or less than I would for sure go with the higher efficiency unit. Keep in mind also that in some states the electricity costs are going to go up by 50% or more in the next few years. You may want to run the numbers at those higher electricity costs. The farther south you live, the more days you will use your air conditioning unit. Therefore it will be more beneficial to get a higher efficiency unit the farther south you live.
Heat Pump units often are rated much higher in efficiency that straight air conditioning units. Especially in the mid to southern climates in may pay to look at a heat pump unit. I will try to address that in the future. Heat Pumps will be a whole separate subject.
So to wrap up the thoughts on air conditioning efficiency. As electric prices rise the cost of the higher efficiency units will be much more practical. Higher efficiency air conditioners have more safety controls built into them. You can do some figuring and find out how much more you can spend for a higher efficiency unit and still get your money back in saved electricity. There are many good, better, best options out there. Ask your contractor to quote the prices for the different efficiency units available. If you do not ask usually the prices will be the down and dirty lowest price he can find unit. That rarely is a good thing. If your contractor does not want to quote prices on higher efficiency units, then find one that will. You will not regret it.
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