Understanding Your Air Conditioner: What is a SEER Rating? What Does Tonnage Mean?

Understanding Your Air Conditioner: What is a SEER Rating? What Does Tonnage Mean?

When you’re trying to choose the best HVAC system for your home, you’re going to run across these two standard air conditioning measurements: SEER rating and tonnage.

If you don’t understand what each means, you could end up getting a unit that doesn’t fully cool your home or one that’s not very energy efficient.

What does each of those terms mean when it comes to home air conditioning? Those are questions we get asked regularly at Air Tech of Central Florida while providing air conditioning services to families in the Orlando area.

Another question we get often while out on AC repair calls is, “How do I know when it’s time to replace my HVAC system?”

Before we get into the basics of SEER and tonnage and what they each mean, here are some telltale signs that it’s time for a new AC unit.

  • A repair would cost more than ½ the price of a new unit
  • Your energy bill is much higher than the norm
  • Your system is needing repairs two or more times per year
  • Your AC uses R22 Freon, which is being phased out
  • Rooms in your home are at inconsistent temperatures
  • You HVAC system is over 10 years old

What is the SEER Rating for Air Conditioners?

The SEER rating is an energy efficiency measurement for air conditioning systems. SEER stands for Seasonal Energy Efficiency Ratio. The higher the rating the more energy efficient the AC unit.

The SEER rating is calculating by taking the cooling output during a typical cooling-season (when the AC is on) and dividing that by the total electric energy input during the same period.

The calculation for the Seasonal Energy Efficiency Ratio (SEER) is as follows:

  1. Take the BTUs per hour for your air conditioner (cooling capacity)
  2. Find the number of watts used per hour for your air conditioner (power input)
  3. Calculate the BTUs per hour used during cooling months (while some parts of the country may use 4 months (1,000 hours), in Orlando, it’s more like 7 or 8 months) and multiply by #1
  4. Find the number of BTUs per hour per year when the AC is used by multiplying #2 by #3
  5. Divide #3 by #4 to get the SEER rating

What the calculations for SEER looks like:

1 = Unit with 9,000 BTUs per hour in cooling output

2 = Unit with 900 watts per hour power input

(Now we estimate how much cooling output and energy input the AC unit has per year)

3 = 1,800 hours (estimating annual cooling hours in warm climate) x 9,000 = 26,200,000

4 = 1,800 x 900 = 1,620,000

5 = 26,200,000 / 1,620,000 = SEER rating of 16.

Less energy efficient units will have lower SEER ratings. Older models typically have a SEER rating of about a 6.

What SEER Rating Should I Use in Florida?

There is a new energy efficiency standard that went into effect in 2015 which dictates the minimum SEER rating for new unit installations. It’s divided per region as follows:

  • North: 13
  • Southeast: 14
  • Southwest: 14

The minimum SEER rating for Florida home air conditioning units is 14.

Why Is It Important to Know the SEER Rating on a New AC Unit?

It will impact the energy used to run your air conditioner. So much so, that it’s against the law for a contractor to install a system that does not meet your region’s minimum SEER rating.

What Does Air Conditioner Tonnage Mean?

Tonnage is one of those terms that can confuse a lot of people. It doesn’t have anything to do with the weight of the unit and instead of about how much heat the unit can remove from your home in an hour.

The measurement came about back in the days when ice was used to help cool homes in the summer. One “ton” of cooling is equivalent to 12,000 BTU/hour, which is the amount of heat it takes to melt a ton of ice in 24 hours.

Larger homes with more space that needs to be cooled, will require a higher tonnage air conditioning unit. Higher tonnage units use more electricity than those with lower tonnage, so it’s important that you buy the right size for your home.

Too small, and your home won’t be sufficiently cooled in all rooms. Too big, and you could be spending more than you should on electricity bills.

What Tonnage AC Unit Do I Need?

Experienced HVAC service providers, like Air Tech of Central Florida, know what size unit is the best fit for your home’s area and layout. Whether we are installing a standard HVAC unit or a mini-split system for a bonus room, we’ll do calculations based upon a number of factors to ensure adequate and efficient cooling for your home.

A very rough estimate is to take your square footage and divide by 1,000 to get the minimum tonnage. But that won’t factor in things like climate, number of windows and more, so it’s recommended to have a professional do the calculations.

Factors that go into deciding the best tonnage for your home include:

  • Square foot area
  • Age and construction style
  • Condition of the insulation
  • Exposure to sunlight
  • Climate Zone
  • Number of sunlight-facing windows

Need Help Choosing a New AC System?

Our experienced, NATE Certified technicians can help you choose the best HVAC system for your family’s needs, keeping budget, comfort, and energy efficiency in mind.

Call us at 407-696-9876 to schedule a free consultation today or fill out our handy online request.

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