# Portable air-conditioning system output problem

I have just bought a potable air-conditioning system for my kitchen. However, after I bought the air-conditioner just realised I need to put the output pipe to the outside. My kitchen doesn’t have any window and it is far from other windows in my house. I understand that air-conditioner doesn’t work properly without connecting it to the outside.

However, my question is, can I put the output to a bucket or tank of water? In that case it will heat up the water instead of the environment.

• Anything like a water bucket or something like that. – Mohammad Jul 28 '16 at 18:22
• Does this unit have the closed pipe, radiator style output or the flexible tunnel, force hot air output? – RomaH Jul 28 '16 at 18:34
• Bubbling warm air through a bucket of water will not be particularly effective at transferring the heat from the air to the water. – brhans Jul 28 '16 at 18:36

As an abstract question, yes you could transfer the heat to water. But in practice it is a totally unfeasible solution. Even a small AC will remove 5k BTU/hr from the air while also generating some heat of it's own. So let's call it 8k BTU/hr total heat generated.

At that rate you would heat 5 gallons of water from 70 ºF to 100 ºF in less than 10 minutes. And that's assuming perfect heat transfer to the water and no heat leakage back into the air.

Sure, you could transfer heat in air to water, provided that you have an underwater radiator duct, an insulated water vessel, and a means to cycle that water periodically.

Without those things the heat that's now in the water will radiate back into the room, simply moving heat around at your expense.

• Thank you for your comment. To make the job easier, do you think is that possible I simply put the output from air-conditioner directly into the bucket or water of something like that and change the hot water with cold let say every 1 hour? – Mohammad Jul 28 '16 at 18:15
• I don't believe that without some sort of high surface area radiator or branched tube array you'll get efficient enough heat transfer to the water. The unit will need to run much longer than normal, and probably won't keep up with solar gain in the room. – isherwood Jul 28 '16 at 18:28

Having had direct experience with indoor use of this type of air conditioner, I can attest to the impracticality of attempting to cool the hot air in the manner you suggest.

If you had the ability to construct a tower, say 2 meters high, 0.5 meters in diameter, with layers of ice within, but held on open racks to enable considerable airflow, the output of the air conditioner may be cooled sufficiently. Of course, the ice will melt and have to be replaced frequently.

A rough guess here, but expect that 10 bags of ice, US standard 8 to ten pounds may last a couple of hours at the cooling rate needed. That converts to 10 to 12 gallons of water melted by the output of the air conditioner.

You would get insufficient cooling from smaller amounts of ice and most certainly insufficient cooling from water, unless you could fashion a method to vaporize the water to relinquish yet more energy. Unfortunately, the vaporized water would have to be ejected outside, or the room in question would become unbearably humid.

I have a gut feeling that my numbers are on the low side, but if the tower provides good circulation, it might be possible. The logistics of installing the ice and having a sufficient supply is a serious challenge as well.

• If you are proposing ice as a solution I don't see why you would need the AC at all, the ice can just cool the air directly. But it's entirely impractical. To match the cooling rate of a small 5k BTU/hr AC you would need about 25 pounds of ice PER HOUR. – Hank Jul 28 '16 at 18:37
• The OP is suggesting to use water, which is even less practical than ice for exactly the reason you suggest. I'm not really proposing it so much as presenting the impracticality of either method. – fred_dot_u Jul 28 '16 at 18:50
• AC units commonly measure cooling capacity in tons (or BTUs... 12,000 btu = 1 ton) that's tons of ice per hour. So for an average 12,000 btu portable AC unit you would need 2,000 lbs of ice per hour to achieve the same cooling capacity... so if you are using it to melt ice, then it would melt about that much (actually, more since the heating capacity is higher than the cooling capacity). – Ben Welborn Aug 3 '16 at 19:11