What the Tonnage of an AC Really Means

question-mark-badgeWhen installing a new air conditioning system or replacing one that’s past the point where repairs will help, one of the important factors for HVAC experts to consider for the new system is its tonnage. You may have heard this term before but not been certain exactly what it meant. It’s a bit confusing, since it sounds like it’s how much the air conditioner weighs. But the weight of the system has nothing to do with it; it’s actually a measure of how much cooling power the unit has. We’ll take a look at what tonnage means and why it’s so important to ensure a new system has the right tonnage to match the house it’s cooling.

What Tonnage Means when Talking about an AC

The first thing to know is that air conditioners don’t “create” cooling. Cooling isn’t a type of energy! To lower the temperature of the air the blower fan will send around the rooms of a house, an air conditioner removes heat from the air along its evaporator coil. Therefore, the best way to measure the cooling capacity of an air conditioner is to measure how much heat it removes per hour. This is a bit bewildering to people at first, since they hear HVAC technicians talking about an air conditioner in terms of heat.

The heat an individual AC removes from the air is measured in BTUs, British Thermal Units. One BTU is equal to the amount of energy necessary to change the temperature of water by one degree, either by adding or removing heat energy from it.

Now imagine a one ton block of ice. The amount of heat necessary to melt it within one hour is 12,000 BTUs. This amount of BTUs is known as a “ton.” If you have an air conditioning system with 4 tons of cooling power, that means it can remove 48,000 BTUs from your house over an hour.

The Tonnage a Home Needs for Comfort

How much tonnage is necessary to make a home comfortable? Most homes use a system between 1.5 and 5 tons. But this isn’t something to make a guess at when installing an AC: tonnage must match the cooling requirements of a space or else it will result in an air conditioner that either can’t keep up with comfort demands or which will waste energy while needlessly wearing itself down. It takes skilled HVAC professionals to match AC tonnage with a home. The technicians perform a heat load calculation that takes factors about a house (insulation, number of windows, amount of heat-producing appliances) to determine the cooling tonnage that hits the sweet spot between too little and too much.

(By the way, all this applies to heat pumps as well: the tonnage for a heat pump is the amount of heat it can either remove from the home or bring into it.)

If you are looking for a heat pump or air conditioning installation in Lebanon, OR, make sure you call on an experienced and professional team to do the job. Speak to one of our professional HVAC installers to get started on properly sizing the new system that will do the job for your home.

Midway Mechanical Inc. has served the Willamette Valley for over 40 years. Give us a call today and experience our company’s exceptional customer service!

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