HVAC tonnage a weighty subject

If a neighbor says he bought a 5-ton HVAC system, he isn’t saying it weighs 5 tons.

In HVAC talk, a ton measures how much heat removed by the system would be needed to melt 2,000 pounds (one ton) of ice in 24 hours. 


The term goes back to the early days of AC, just as horsepower was used to explain the first automobiles’ power and candlepower was used to describe the early electric lights’ capacity.

Tonnage serves as good shorthand if you’re looking for a new system, but don’t be guided by the basics alone. As many Facebook relationships say, “it’s complicated.”

Generally speaking, a ton will cool 400 to 600 square feet of a residence. So if your home covers 2,000 square feet, you can estimate that you will require about 5 tons of air conditioning capacity.


This is where you need to call a licensed contractor who has installed many HVAC systems.

That’s because numerous other factors go into correctly sizing a new system. Tonnage alone is not the correct answer.

You need to calculate the quality of your insulation, the number and size of windows and doors, the ceiling height, the home’s placement (north, south, east, west), tree coverage, room sizes, ductwork and several other issues.

Then he can do a “Manual J” calculation that tells you how many tons you really need – maybe more, maybe less.

And you don’t want the wrong size HVAC system. One too large will cost more and require more power, and one too small won’t do the job right.

Premier HVAC’s veteran technicians are authorities on sizing and installation. We do both residential and commercial HVAC (which has very different considerations from a home unit.) We serve Long Island, Manhattan, Queens and Brooklyn, which is our home base.