# 1/3 gallon of water at 55F can cool 5000 cu ft room from 80F to 79F? [closed]

I calculated that a mere 1/3 gallon of water at 55F could cool down a 5000 cu ft room from 80F to 79F (under admittedly inaccurate simplifying assumptions).

Does this even sound reasonable? I'll cut/paste my calculations here on request, but I sense I'm an entire order of magnitude off and just looking for a quick "no way" or "that sounds about right".

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 Do you mean you cool the room by evaporating the water i.e. the latent heat of vaporisation of the water is equal to the heat lost when cooling the air by 1°F? If so a quick stab at the calculation suggests you need to evaporate 290g of water and this is a bit less than you suggest, but of the same order of magnitude. – John Rennie Jun 10 '12 at 19:24 Actually, I just mean the energy the water must absorb to go from 55F to 79F (ie, 1 calorie per gram per degree Celsius), no vaporization involved. – barrycarter Jun 10 '12 at 19:29 In that case I make it about 3.1kg, which is larger than you get, but I'm not used to working with cubic feet and fahrenheit so I may well have made a slip somewhere. – John Rennie Jun 10 '12 at 19:34 No hang on (damn I hate non-SI units :-) I think it's about 1.8kg of water and I think a US gallon is 3.8 kg so it's just under half a gallon. – John Rennie Jun 10 '12 at 19:44 @barrycarter What you've just noticed is that (1) the specific heat of water is very high (2) the specific heat of air is low and (3) the density of liquid water is much higher than that of air (which matters because it is mass not volume the controls the total heat capacity). – dmckee♦ Jun 10 '12 at 19:49