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McGarry and Madsen's home inspection blog for buyers of
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How many tons is my Cumberland air conditioner or heat pump?
Monday, April 8, 2019
You can determine the size in tons of your Cumberland HVAC system by examining the model number on the data sticker at the side of the condenser (outdoor unit). Look for a cluster of numbers at the center of the model number, and two of the digits will be a number divisible by 6 or 12, which represents the nominal BTU of the system in thousands. A ton of air conditioning equals 12,000 BTU, and 30 divided by 12 equals 2.5, so the data plate below indicates the system is 2-1/2 tons.
Here’s a rundown of the range you will encounter: 18 = 1.5 tons, 24 = 2 tons, 30 - 2.5 tons, 36 = 3 tons, 42 = 3.5 tons, 48 = 4 tons, and 60 = 5 tons.
If you are unsure whether you have found the right two numbers, you can double-check it by looking for the “RLA” rating on the data plate. RLA is an acronym for Rated Load Amperage, and is what the maximum amperage should be when the condenser up and running. If you divide the RLA by 6 for older units and 5 or 6 for newer units, you should get a number that approximates (not exactly) the tonnage of the system. Make sure you use RLA and not LRA, Locked Rotor Amperage, which is the surge of amps necessary to overcome inertia and start the system. It averages around five times the RLA.
To determine the age of a Cumberland system, go to our blog post How can I tell the age of a Cumberland air conditioner or furnace from the serial number? To find out the age of another brand of air conditioner or heat pump, go to How do I determine the age of my air conditioner?
To learn more about heating and air conditioning systems, see these other blog posts:
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