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Blogs from November, 2021

spoon of alphabet soup

Lost in the alphabet soup of HVAC jargon?

Don’t feel bad if you every time you look at an article about air conditioning or HVAC matters, you give up because you don’t understand the acronyms. Trying to decipher meaning is impossible if you haven’t been exposed to the specialized jargon.

It’s like slurping up that old-fashioned alphabet soup where every spoon is filled with letters that combine to make gibberish!

Vocabulary matters, especially when it comes to figuring out the pros and cons of an air conditioning system.

Here are four essential alphabet terms to help you relate to your air conditioner:

1. SEER:

(No. Even though the term sounds like a soothsayer or a voyeur, this SEER is neither.) SEER stands for Seasonal Efficiency Energy Rating. Basically, it’s how efficient your system is based on the average temps of an entire season. Trane defines it this way:

"A SEER ratio is calculated over an entire cooling season using a constant indoor temperature and a variety of outdoor temperatures ranging from 60 degrees to 100 plus. This is how it simulates a typical season."

The newer and more efficient your AC unit is, the higher the SEER will be.

Years ago, there was no minimum standard, but in 1992, the government declared that every unit installed had to be at least a 10 SEER. Fourteen years later, in 2006, the standard went up to 13 SEER, so now every new furnace installed has to be at least a 13 SEER.

The truth of the matter is, though, that a SEER rating of 13 is the lowest efficiency rating allowed. In 2021, you can purchase a unit with a SEER rating as high as 27. The higher the SEER, the lower your costs to run the system.

Think of the SEER rating of your furnace or air conditioner like a Miles Per Gallon rating for a car. The newer and more efficient your car, the more money you save on gas.

The optimal SEER rating for a home varies depending on the geographic region, but here in hot, humid Florida, the higher the SEER, the better.

In 2011, the requirements for SEER went regional, and Florida began installing only units with a SEER rating of 14 or higher.

By 2023, the minimum requirement for new unit installations in Florida is a SEER rating of 15. 

2. CDD

A lot of times when manufacturers and companies discuss their units, you’ll hear the term CDD.

Not CBD.

Not OCD.


CDD is an acronym for Cooling Degree Days, which calculates the number of days with average temps over 65 degrees Fahrenheit, taking into account the high and low temps of the day. The National Weather Service Explains it this way:

Degree days are based on the assumption that when the outside temperature is 65°F, we don't need heating or cooling to be comfortable. Degree days are the difference between the daily temperature mean, (high temperature plus low temperature divided by two) and 65°F. If the temperature mean is above 65°F, we subtract 65 from the mean and the result is Cooling Degree Days. If the temperature mean is below 65°F, we subtract the mean from 65 and the result is Heating Degree Days.

Example 1: The high temperature for a particular day was 90°F and the low temperature was 66°F. The temperature mean for that day was:

( 90°F + 66°F ) / 2 = 78°F

Because the result is above 65°F:

78°F - 65°F = 13 Cooling Degree Days

Don’t sweat! I’m not going to make you take a test or anything! The point of this is that the more Cooling Degree Days you have, the higher your costs to cool your home will be.

Guess what? The number of Cooling Degree Days is increasing over time, due to global warming which is causing higher temps and more days over 65 degrees.

3) BTU

BTU stands for British Thermal Unit, and it’s the amount of heat that’s needed to raise or lower one pound of water by one degree Fahrenheit.

Think of it as a way of measuring how much energy it takes for your air conditioner to pull heat out of the air.

BTU is a measurement used worldwide to gauge energy transfer in all kinds of appliances, furnaces, and air conditioners.

You need to match the BTU’s of a unit to the size of your home, so that you don’t spend more energy than you need to extracting the heat from the air around you.


Not Merv Griffin. Not a swerve or a curve or a nerve. Just MERV.

MERV stands for Minimum Efficiency Rating Value, and it’s used to rate the efficiency of air filters. You know that changing your air filter is one of the best things you can do to keep your system in good working order.

You’ll keep your system in even better working order if when you change air filters, you use one with high MERV rating.

In general, a pleated filter has a MERV rating of 8. Anything above that is high efficiency and good quality for residences. Rooms that are required to be dust-free, like surgery rooms and computer server rooms, use filters with a MERV rating of 17-20.

Don’t let the alphabet soup talk of the HVAC industry choke you up!

Let ServiceOne explain your air conditioner and furnace to you. Call us for a Precision Tune-Up, a question, or a quote.

We’re here to serve you.


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