Terms like SEER and tonnage get thrown around a lot in the HVAC world. If you’re in the market for a new air conditioner, you’ve likely heard them. But, you may not know what they mean or why they’re important.
Understanding these go a long way toward picking out the right unit for your home or business. These terms tell you how powerful of an A/C you need and if they may also save you a little bit of money.
Let’s take a look at what these terms mean and how you can use them to choose your new HVAC equipment.
What does tonnage mean for an air conditioner?
The tonnage of an air conditioner measures how much heat it can remove from an area in the course of one hour. It’s based on the word “ton,” but has nothing to do with the weight or mass of the a/c itself. Instead, one “ton” here can remove 12,000 British Thermal Units, or BTU’s, every hour.
A Btu is a measure of heat. Specifically, it’s the amount of heat that’s needed to increase the temperature of a pound of water by one degree Fahrenheit.
Understanding this can help you choose a new central air system. You want one with tonnage that matches the square footage of your home. Too little and the system won’t cool your house properly. In fact, it might even break down quickly if it’s always working too hard. Meanwhile, too much and you’re wasting energy.
The average home requires one ton of air conditioning per 400 to 1,000 square feet. That’s a lot of variation, but the need is affected by how many windows are in your home, the height of the ceiling and how easily air flows through the house.
What is an air conditioner SEER rating?
SEER stands for “Seasonal Energy Efficiency Ratio.” It’s a measure of how much energy an air conditioner uses to operate over one year. The ratings range from 13 to 25 for central air units. The higher the rating, the less energy they use.
The main components of this rating are Btu’s and kilowatt hours — kWh for short. For the SEER rating, we combine the amount of heat the system removes with the amount of energy the unit uses.
That energy is the electricity running the a/c. Electricity in the home is measured in kWh. To get the rating, you look at the Btu’s the unit can remove over the entire cooling season. Then, divide that by the number of kWh it takes to do so.
How can an Air Conditioner SEER rating save me money?
A SEER rating measures how much energy your air conditioner uses. The higher the rating, the less energy the unit uses. Less energy means lower monthly utility bills, and who wouldn't like that? Therefore, buying an AC with a high SEER rating will result in lower energy bills than with a less-efficient unit. You can also get rebates for installing high-efficiency models.
In 2008, the U.S. Department of Energy made a new requirement for central air units. Under this new law, they all need a minimum rating of 13. Before that, central air systems had ratings as low as 6.
After that, there’s the Energy Star program. It’s run by the Environmental Protection Agency and identified high-efficiency appliances. This includes HVAC units.
To be certified for an Energy Star rating, an appliance must use less energy than comparable units. An a/c rated 14.5 or higher is recognized by the Energy Star program for high efficiency.
It’s also important to note that window or wall-mounted room units are not affected by this requirement. Most of those have a rating of around 10. So, virtually none are nearly as efficient as central air.
Of course, those units cost much less than installing or replacing central air. But, they don’t cover the whole house. And, over time, they’ll cost much more in energy bills.
Meanwhile, systems with high ratings often cost more money than those lower ratings. When choosing one, then, you may have to balance that with your budget.
However, a higher rating may also make things a little easier on your wallet up front. Today, many energy companies around the country are urging people to buy energy-efficient HVAC equipment. They do so with cash rebates.
Check with your local electricity provider and other local energy groups. They may offer cash rebates for installing a high-efficiency or Energy Star-certified unit. These can range from a few hundred dollars to a thousand or more.