When I see these multi-ton units, what does the number mean? Obviously the machine doesn’t weigh that much.
That’s the amount of ice the machine could make from 32F water in 24 hours. It’s an old specification. A 30 ton unit is 360000 Btu/hour. A pretty big unit.
OK, 'nother question. Why would you rate A/C at Btu? I thought Btu was a measure of heat production.
Btu is a measure of heat - for A/C units, BTU/hour is how much heat it can move in an hour.
Right. Think of Btu as a quantity of heat like a gallon is a quantity of water. 1 Btu/hour for an AC is analagous (in the strictest sense in this case) to 1 gal/hour for a pump.
An A/C unit does produce heat. The more heat it produces outside, the more cool air it can produce inside. You can’t get sumpthen fer nuttin’.
Never heard it expressed that way. I’ve always considered 1 ton of cooling to be the amount of cooling produced by the melting of 1 ton of ice in a 24 hour period. Wouldn’t ice production be variable based upon machine efficiency, ambient temperatures, and so forth?
This curious comes about because the first air conditioning systems actually did cool the air by melting ice.
It takes the same amount of heat to melt ice as it does to make ice. The specification is of the output capacity of the machine. The input power required to produce this output depends upon the efficiency.
I’m pretty sure the specification arose because of the imagery. The nontechnical can visualize the making, or melting, of ice and thus the cooling effect while taking Btu’s out of the building and moving them to the outside is mostly ncomprehesible.
Oops, I see I garbled the last sentence of my previous post.
I believe the spec is not just due to imagery, but rather that in the first indoor air cooling systems, melting ice actually provided the cooling, much as the ice box preceded the refrigerator.