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Touchstone Heating & Air Inc. Blog

What Does “Tonnage” Mean for Commercial HVAC?

AC-units-on-roofWe offer service for light commercial HVAC in High Springs, FL. “Light” commercial means we work with AC and heating units that are 25 tons and under. No, that doesn’t have anything to do with how much the equipment weighs. The “tonnage” of a system is a bit more complex, and it has to do with the amount of heating and cooling an HVAC unit can provide. 

This applies to residential ACs and heaters as well, so even if you don’t own or operate a commercial facility, you may wish to stick around and learn about how professionals determine the amount of power necessary to provide climate control for a building.

Tons of Cooling, Tons of Heating!

The tonnage of a system is a handy description for HVAC professionals to express the capacity of an HVAC unit to either remove heat from a building (cooling) or add heat to it (heating). The standard measurement of heat (either added or subtracted) is the British Thermal Unit or BTU. A BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. 

If you look at a small window air conditioning unit, you’ll see BTUs listed on it: that’s the amount of BTUs of heat the AC can remove from a space over an hour. Most window ACs can remove about 5,000–6,000 BTUs per hour. But when you start moving to any system larger than window air conditioners, you’ll be dealing with extremely large numbers. For example, a standard light commercial air conditioning system may remove 240,000 BTUs an hour. 

Here is where the ton comes along: it’s an easier measurement than using the smaller BTU. One ton is equal to 12,000 BTUs removed per hour. Residential air conditioners are between 1 to 5 tons. Up to 25 tons is light commercial, and anything above that is considered a heavy commercial or industrial system.

But Why Is It Called “Tons”?

Yeah, it does sound strange. But there’s a reason for it, and the reason 12,000 BTUs was selected as the base unit for heat measurement: 12,000 BTUs is the amount of heat necessary to melt one ton of ice at 32°F in 24 hours. This measure was set by the American Society of Refrigerating Engineers way back at the beginning of the century, and we’re still using it. (Except for small equipment like window ACs, which are only fractions of a ton.)

Professionals and Proper Sizing

If you’re wondering how many tons of heating or cooling your commercial business requires, we have good news: you don’t have to worry about that when it comes to installing or replacing equipment. This is a job for professionals who have special training on how to “size” HVAC equipment for many different types of spaces. If you own or operate a small business and are looking for new HVAC equipment, you only have to get in touch with our light commercial experts. They’ll do a special “heat load calculation” to determine the proper tonnage necessary for comfort and energy savings. 

Call Touchstone Heating and Air Inc 24/7 for exceptional customer service!

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