If you have been in the market for a new central air conditioning system, you have been doing research online or getting quotes from a few HVAC companies installing new systems. Undoubtedly, you have been hearing terms like SEER and EER ratings. What is the SEER rating (pronounced like a steak you’d “sear” to perfection), and what influences the actual rating of the system you will buy?
Using a quote from Trane.com, “The SEER measures air conditioning cooling efficiency, which is calculated by the cooling output for a typical cooling season divided by the total electric energy input during the same time frame. A SEER rating is a maximum efficiency rating, like the miles per gallon for your car.”
If you go on to AHRI Directory to find out what is involved in measuring these SEER ratings, you’ll find terms like Wet-Bulb, Dry-Bulb, Static Pressure, Enthalpy, Steady-State Tests, and Cyclic Tests. But it really comes down to a few things.
- The outdoor condenser coil.
- The indoor evaporator coil.
- The compressor.
- The blower motor in the furnace pushing the air across the coil.
The condenser coil – Ever wonder why the outdoor air condensers we are installing today are larger than the ones 20 years ago? Heat transfer and surface area. The outdoor condenser coil can take the heat absorbed inside and get rid of it easier when the unit’s surface area is larger.
The evaporator coil – Jeez! Talk about getting larger. The evaporators are almost as big as the furnaces we are installing today. Some of the larger evaporator coils are 30 inches tall or more. Again, it’s all about efficiently absorbing heat and humidity from the house and sending it outside.
The compressor – Today’s modern scroll compressors have minimal moving parts. There are single-speed compressors, two-speed, all the way up to fully modulating. The scroll compressor can move more refrigerant in a single cycle than previous versions, like the rotary and piston compressors.
The blower motor in the furnace – Motors are more efficient when they run at lower speeds. A 3-ton air conditioner blower motor will run at one amperage, while a 5-ton blower motor, with its speed taps adjusted down to a 3-ton capacity, will run at less amperage than the 3-ton motor. That lowers the amount of energy used by the system, increasing its SEER rating.
SEER ratings on AHRIdirectory.org
Let’s look at the SEER ratings on AHRIdirectory.org for a Trane split system where the AC/condenser is located on the side of the house, and the furnace is located in the garage, closet, or attic.
In the example, we have the same 4TTL6036A1 condenser. In model number nomenclature, the first “6” in “6036” means 16 SEER. The “36” stands for 36,000 btu capacity – a 3-ton system. We can adjust the actual SEER rating of this “16 SEER” condenser by changing the evaporator coil and furnace matched up with it.
So, unless you see the actual copy of the AHRI certificate listing the model numbers of the furnace, condenser, and evaporator coil, you might think you are buying a 16 SEER 3-ton split system but only be getting a 15.50 SEER system. Then again, if your contractor matches that outdoor unit up with a larger furnace and coil, you could be getting an even more efficient system than 16 SEER.
Let’s get into how higher SEER systems save you money in the long run in another blog, but for now, I wanted to share this particular information.