The size (cooling capacity) of your air conditioner is determined by the amount of Btu (British thermal unit) and the Tonnage (12.000 Btu = 1 Ton). I also laughed out loud. Photo of blue ice by ezioman from, used under a Creative Commons license. What amount of Btu and Tonnage should your air conditioner have in order to properly cool your home? So now you are likely asking, what is a BTU? Expanding a bit further on grusso's question... when folks had to physically handle their energy source around (e.g., ice), a daily metric seemed appropriate, e.g, tons of ice a day. He was an HVAC contractor and said he was installing a new air conditioner for an elderly woman. Proudly Serving Thanks. Name (required)Phone (required)Email (required)Message (required) I am in Sarasota or Charlotte County, FL. I laughed out loud about Abe's quote and the credits! The discussion of whether to use 143.5 or 144 BTU/lb for the latent heat of fusion of ice is pretty nerdy stuff. The Magic of Cold, Part 1 - How Your Air Conditioner Works. Bless you, Allison for bringing unanticipated joy to my day! Yo, Alison. It sounds likely, but their numbers don't work out, so I'm gonna go with Honest Abe on this one and remain skeptical. And if you figure out what 'heat of zaporization' is, let me know! Tons is a shorthand phrase that refers to the total cooling capacity of the unit in BTU’s. What Causes An Air Conditioner To Freeze Up? Thanks for that link to an original source from 1920. Yeah, you did mention nominal capacity, etc... just to say "Let's ignore..." I'll be looking for your blog on that subject. Likewise, a “2-ton” central air conditioner is able to cool 24,000 BTUs per hour. © Copyright Kobie Complete, 2020. Check out our extended glossary to learn more about other HVAC terms. One ton is the ability of your air conditioner to cool 12,000 BTUs (British Thermal Unit) in an hour. How does an air conditioning system actually work to cool the air in my home. No-Cost 10-Year Parts and Labor Warranty* if 12,000 BTU = 1 ton why would I need 80,000 BTU for the 3 ton system I am about to have installed? A 4 ton air conditioner is one that can remove 48,000 BTUs of heat per hour from the house. What I am having a hard time understanding...and maybe it's because I didn't read closely enough or I just don't have the brain capacity to figure it out...but why if the whole thing came from a ton of ice melting in a 24 hour period...which would mean 12,000 BTUs per hour, do we refer to a ton of HVAC capacity as only 12,000 BTUs and not 188,000 BTUs which is where the ton of ice is? OK, so people used to cool and refrigerate with ice. So the heat pump and air handler will consume ~2.8 kW (36,000 / 13) at those conditions. How Many BTU’s Do I Need On My Air Conditioner? Hmm... and just when I thought you were going to demystify nominal capacity vs. AHRI capacity vs. design capacity. Apply the tonnage to the space. In air conditioning jargon, then, a ton of AC capacity is equal to 12,000 BTU/hr.