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Building Science

How Many Tons of Air Does a 2.5 Ton Air Conditioner Move?

And under what conditions would it move exactly 2.5 tons of air?

How much air does the blower in a 2.5 ton air conditioner move in a day?
Image Credit: Image #1: Grainger catalog

We live in this invisible stuff called air. (But of course you knew that.) We pump it into and out of our lungs. We exhaust it from our bathrooms and kitchens. We cycle it through our heating and air conditioning systems. If we’re lucky, we live in a home that even brings outdoor air inside as part of a whole-house ventilation system. But we’re missing something.

Air seems insignificant. Even though we’re immersed in this fluid continuously, it seems to have no substance. After all, we move through it without noticing it most of the time. But air really is quite substantial. It has weight. It requires work to move it around. It takes energy, even when we’re not heating or cooling it.

Let me see if I can help you get a feel for the weight of air. If you live in a home with a forced air heating or cooling system, that system has a blower. The one shown above is typical. It pulls air through the return ducts and into the furnace or air handler. There, it does its heating or cooling magic and sends the air on its merry way back to you through the supply ducts.

A fairly typical size for a blower is one that moves 1,000 cubic feet per minute (cfm). How many pounds of air would it move in a day if it runs continuously? Before you scroll down to look at the answer, though, really think about this. Come up with a guess in your mind. How many pounds of air does your air handler move in one day? Write it down.

Got that number? Good. Let’s find out how close you are. We just need to do a little bit of easy arithmetic.

We may as…

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One Comment

  1. Andy Kosick | | #1

    Couldn't help myself
    As a home performance professional that also does a little bit of SCUBA diving I find this quite fascinating and couldn't help but wonder what the weight of air in the average house is. Average or not, I went with the 12,672 cubes in a typical Habitat for Humanity house on a conditioned crawl. This came to 950.4 pounds, that's almost half a ton of air. With that in mind the fact that air is pushing against us with about 14.7 PSI of force (at sea level) sounds more reasonable. Divide that 0.47 tons into the 13 tons of air for a 1000 CFM blower running at 25% (a likely scenario in a well insulated house this size) and the blower is only moving all the air in the house about 27 times. I thought that compared to all the other numbers here that one actually seemed kind of small.

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