Considerations - Central Air Conditioner

So you're shopping for a central air conditioning unit. This is a topic that doesn't have a lot of information available online.

Part of the reason for that is because it changes frequently, as products and government standards change, and part of it is that so much of the quality of the final installed product is dependent on the installer and the quality of the job they do. And also, because there really isn't that much difference between what the various companies offer.

Once you've got the Sizing and SEER rating decided on, it's probably better to find a good local installer and let them recommend a brand based on their experience, than it is to pick based on brand first.

This article covers a specific subset of air conditioners: External air conditioners that you'd use to cool an average residential building (ie, your house).


Air Conditioner

Air conditioner capacity is measured in tons. One ton of air conditioning capacity means it can remove 12,000 BTUs worth of heat energy per hour. A BTU is the amount of energy needed to change the temperature of one pound of water by one degree Fahrenheit.

A rough sizing guide is 1 ton per 1000 square feet, so a 2400 square foot home would use a 2.5 ton air conditioner.

SEER Rating

SEER stands for Seasonal Energy Efficiency Rating, and it's designed to make it easy to see which products are more efficient. SEER 10 was commonly used a few years ago, but now government regulations are requiring new units in North America to be SEER 13.

Making a more efficient air conditioner costs more. The compressor and fan needs to be more efficient, and you need more grill space to run air through. But fortunately, the payoff is there.

A 13 SEER unit costs about 20% to 30% more than a 10 SEER unit, but is approximately 30% more efficient. This means the extra money you paid up front will be returned to you in just a few years, and after that you're definitely saving money with the more efficient unit. 13 SEER is the minimum today, but you can opt for even more efficient units - but expect to pay a lot more, and you may not make back the extra money you spend as quickly, if at all.


There are only a few major manufacturers, but they sell their products under many brand names. Some of the major manufacturers are Carrier, Lennox, Amana, Trane, Ducane, Goodman, Keeprite. Goodman is somewhat unique in that it is a family-owned, private company.

Choosing a brand is difficult because really, there isn't much differentiation, and from what I've been able to determine, they all make reasonably good products. A central air conditioner is an expensive purchase, but it's a simple, well-understood device that many companies are good at manufacturing.


Expect a long warranty on a central air conditioning unit. The average lifespan for one of these units is 18 years, so a company should be willing to give you a warranty at least 5 years long; some offer more, some offer parts & labour, others offer just parts. Another thing you can find is a lifetime warranty on some parts, like the compressor, although the "lifetime" is usually limited to the original owner

Labour almost always costs more than parts, so a warranty that includes both is valuable.


Installing a central air conditioner is, in theory, simple. You put the main unit outside, you put the evaporator coils in the air ducts near the furnace, and run pipes between them. Running pipes between them is the hard part here, because this means getting pipe from outside your house to the furnace.

If you have an unfinished basement, this is easy; if you have a finished basement, then you'll want an installer who can work with that to minimize the damage that will be done to the finished portions of your house.


Central air conditioners are usually either placed directly on the ground, placed on somes of structure built for them, or be mounted on brackets secured to your house.

It's important that air be able to move around the unit, because this is how the air in your house gets cooled - heat moves through the pipes out of your house and through the thin metal grille that surrounds the air conditioner. Air needs to move through this grill and out the top of the unit efficiently - so you don't want to stick it in a corner or right next to the house.

Mounting brackets that bolt to the foundation of your house and have arms for the air conditioner to sit on are commonly used for new installations. Having the air conditioner slightly above ground increases the airflow, which contributes to better efficiency.


Most units are within a small range of noise levels, so the amount of sound a unit generates isn't a significant differentiating factor. No unit is going to run silently. The best thing you can do is put it somewhere where you're not going to be bothered by the noise.

If the sound bothers you, you can get a sound jacket that surrounds the compressor and insulates it somewhat, to reduce the amount of noise it makes. This is an inexpensive option, around $75.


Price is based on the SEER rating of the unit more than it's brand. All the units with a particular SEER rating are around the same price, so once again, it's not really a deciding factor.

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