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How many tons is my NuTone heat pump or air conditioner?
Tuesday, November 3, 2020
You can determine the “nominal” condenser tonnage of your HVAC system by examining the model number on the data plate at the side of the condenser (outdoor unit). Just like the nominal size of lumber or an air conditioning filter, the exact cooling capacity may be a little more or less than the nominal rating, but it’s close.
For NuTone, you should look for the two numbers in the second cluster of digits of the model number, which will be divisible by 6 or 12, and 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. Newer units may even state the size in parentheses after the model number, like in the example below.
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 year of manufacture of a NuTone system, see our blog post How can I tell the age of a NuTone heat pump or air conditioner from the serial number?
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To learn more about heating and air conditioning systems, see these other blog posts:
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