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AC Tune Up
May 15, 2019

Understanding SEER Ratings for an Air Conditioner

If you’re shopping for a new A/C, you likely have run into a number that varies among models. This
number is called the SEER rating – Seasonal Energy Efficiency Ratio – and it is measured by taking the
ratio of the cooling output of an A/C over a cooling season and dividing it by the energy the unit
consumes in Watt-Hours.

That all sounds good, but what does it mean in English?

Basically, a SEER rating measures a unit’s efficiency. Here’s what else you need to know to make an
informed choice about a new A/C unit and how SEER ratios come into play.

Understanding SEER Ratios for A/Cs
It’s important to remember that this number is an average – and there are many variables that go into
calculating that average. For instance, it’s created over a cooling season using a constant indoor
temperature and a variety of outdoor temps that range from the 60s into the 100s degrees. The cooling
season is taken by considering the average length and temp of a season.

Newer systems generally have a minimum SEER value of between 13 and 14; the number depends on
certain state requirements. However, a minimum SEER value doesn’t mean it’s a low-efficiency model or
that it’s a cheap version. Maximum SEERs are between 21 and 25. Keep in mind, too, that a SEER rating
is not a constant – it’s a maximum rating. A unit with a rating of 21 can be as high as 21, but it’s not
always running at 21 SEER.

It’s similar to how we measure gas mileage for a car. Even if you have a car with good gas mileage, if you
drive it fast, then slow and fast again, you won’t get the most efficiency in terms of gas usage – even
with a good MPG for your vehicle. It’s the same for SEER values. If you change the temp of your home a
lot or the weather outside your home changes dramatically during the day, you may not get the full
potential of your SEER value.

When to Consider a Higher Seer
Unlike other types of ratings, the highest SEER value isn’t always the best option. The truth is, energy
usage is what costs money – and a SEER value can’t predict usage. Remember that SEER isn’t a fixed
number. It doesn’t run at 21 when you use your unit. Determining when to invest in a higher SEER rated
unit depends on a few things, like your location, your usage, how much shade you get, and other
variables. Remember that a SEER rating isn’t about the quality of the unit – it measures efficiency – and
that measure is based on averages.

High SEER ratings are an easy way for manufacturers to upsell a system, so it’s important to do your
research, but you don’t have to do it alone. A good SEER ratio generally starts at 14, but the higher the
number doesn’t necessarily mean the best system for you. There are ways to calculate the best SEER
rating for your home, but a professional is best equipped to input the values into that calculation
because they understand what it means to buy a unit in your area and with your home.
SEER values aren’t the only way to choose a system. Talk to one of our professionals to understand SEER
ratios, other crucial variables that go into the purchase of an A/C system, and what it all means for you.

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