How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
What size in tons is my Day & Night heat pump or air conditioner?
Wednesday, May 20, 2020
You can determine the size in tons of your Day & Night HVAC system by examining the model number on the data plate at the side of the condenser (outdoor unit). Look at the 3-digit cluster of numbers in the middle of the model number that are divisible by 6 or 12. The second and third digits will be a number divisible by 6 or 12, and represents the nominal BTU of the system in thousands. A ton of air conditioning equals 12,000 BTU so, for the model number C4H360GKD400, 60 divided by 12 equals 5 tons. Another example is CSH648GKA, which is 4 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 Day & Night system, go to our blog post How can I tell the age of a Day & Night heat pump or air conditioner from the serial number? For the age of another brand or manufacturer, go to our blog post How do I determine the age of my air conditioner?
And to figure out what all the other numbers listed on the condenser data plate mean, go to our blog post How do I understand the air conditioner or heat pump condenser label (data plate)?
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To learn more about heating and air conditioning systems, see these other blog posts:
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