Understanding Air Conditioner Rating

When Willis Carrier Invented Modern Air Conditioning in 1902, it changed the way we live. In the wake of the creation of this modern marvel, we have often wondered why Air Conditioning units are measured in tons. Today, we will explore why AC units are rated this way.

Prior to Willis Carrier's invention of modern air conditioning, buildings were cooled in the summertime with large blocks of ice processed from the winter. Typically, a ton of ice would take 286,000 BTU's to melt completely. A BTU, or British Thermal Unit is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. If we look at this in a 24-hour period, 286,000 BTU/24 Hr. = 11,917 BTU/hr. In the heating and cooling industry, that number is rounded up to 12,000 BTU/hr. 

So, if we look at the Carrier Infinity 24VNA9 air conditioner, the number 24 indicates that this model is capable of 24,000 BTU's. So we divide 24,000 BTU's by 2 to get 12,000 BTU's. This indicates that the 24VNA9 is a 2-ton unit. 

SEER Rating is the Seasonal Energy Efficiency Ratio, is the cooling output in a a nominal cooling season, divided by the total electric energy used in the same period. In other words, it is the BTU output per cooling season divided by the kW used to create this cooling. 

The Higher a units SEER rating, the more efficient the unit. For example, The Carrier 24VNA9 has a SEER Rating of 19 SEER. By Contrast, the Carrier 24ANB1 system has up to 21 SEER, being even more efficient. 

Great Lakes Home Comfort can help you to find a reputable, certified and trained dealer for your central air conditioner in Michigan and Northern Ohio. Find out more about central air conditioning here.