Comments on: Why Is Air Conditioner Capacity Measured in Tons?

By: koushik

koushik — Wed, 28 May 2014 20:10:55 +0000

awesome explanation
awesome explanation

By: Jim Smith

Jim Smith — Sun, 11 May 2014 22:40:17 +0000

Enjoyed the post, Chaucer
Enjoyed the post, Chaucer included. Made me wonder exactly how the cooling worked, so I started looking and found that new buildings are also implementing ice cooling systems ! Fascinating..
http://home.howstuffworks.com/green-living/ice-block-ac.htm 

By: David Butler

David Butler — Tue, 04 Feb 2014 21:15:08 +0000

@Engr Stev: The formula to
@Engr Stev: The formula to convert to kW on your website is incomplete. It leaves out the the AC's efficiency (EER), which varies with indoor and outdoor temperature, indoor RH, and airflow.

For example, a mid-efficiency 15 SEER 3 ton heat pump has an EER of about 13.0 at standard AHRI conditions (95F/75F/67F). So the heat pump and air handler will consume ~2.8 kW (36,000 / 13) at those conditions.

By: Engr Stev

Engr Stev — Tue, 04 Feb 2014 00:10:05 +0000

Good explanation…although..
Good explanation…although…you can see more explanation about the rating of air conditioner in ton…here..
http://www.electricaltechnology.org/2014/02/why-AC-rated-in-Tons-Not-in-kW-or-kVA.html

By: Faisal

Faisal — Sat, 13 Jul 2013 10:06:38 +0000

Thank you very much, it was
Thank you very much, it was very helpful....

By: anupam

anupam — Mon, 13 May 2013 12:49:21 +0000

What is ton in AC..plz explin
What is ton in AC..plz explin details..

By: David Butler

David Butler — Sun, 23 Sep 2012 05:44:17 +0000

Expanding a bit further on
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. So in that sense, tons of ice was also a rate. But when automatic energy conversion systems like compressors entered the scene, engineers standardized on hourly rates, pretty much across the board.

Yo, Alison. Yeah, you did mention nominal capacity, etc... just to say "Let's ignore..." I'll be looking for your blog on that subject.

By: Allison Bailes

Allison Bailes — Sun, 23 Sep 2012 01:22:55 +0000

grusso:
grusso: You ask a great question, and it's not because of lack of brain power on your part that this doesn't make sense. It's because of laziness on the part of a lot people who talk. It happens for the same reason that builders and other folks who work with areas all the time say a house is '2500 feet' when they really mean it's 2500 square feet. A ton of AC capacity, as you (almost) correctly state, is 288,000 BTUs, sort of. But it's a rate, not a quantity, and a ton of AC capacity has been defined as 288,000 BTUs melting over 24 hours, or 12,000 BTUs per hour. Without the 'per hour' in there, it looks like a quantity, but it's really a rate.

By: grusso

grusso — Sun, 23 Sep 2012 01:08:14 +0000

Very Interesting! Thanks.
Very Interesting! Thanks. 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?

By: Allison Bailes

Allison Bailes — Sat, 22 Sep 2012 15:18:32 +0000

David B.:
David B.: Hey, I did mention that issue here! It's on my list to cover.

Yes, that's exactly what I was referring to when I said, "their numbers don't work out." Thanks for that link to an original source from 1920. The discussion of whether to use 143.5 or 144 BTU/lb for the latent heat of fusion of ice is pretty nerdy stuff.