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.

Your comments will be much appreciated.

  • Anything like a water bucket or something like that.
    – Mohammad
    Jul 28, 2016 at 18:22
  • Does this unit have the closed pipe, radiator style output or the flexible tunnel, force hot air output?
    – RomaH
    Jul 28, 2016 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, 2016 at 18:36
  • 1
    Frame challenge. Your true problem is "How do I cool my kitchen? Common air conditioner solutions all seem to require a nearby window, and there are no windows in or near my kitchen." - The solution may or may not involve a portable A/C. Jun 20, 2021 at 18:27

6 Answers 6


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.



Does your kitchen use gas burners? If you do setup a portable air conditioner that exhausts air to the exterior, you will need to check and make sure you're not creating excessive negative pressure in the room, which can interfere with gas appliance operation and lead to issues with carbon monoxide build up.

Short answer

No, most portable air conditioners are not designed to transfer exhaust heat into a body of water.

Knowing nothing else about the layout of your building or the restrictions you're working with, if you need to cool a room without windows using a portable air conditioner, you might find success by placing the unit at the window closest that room, then cycling the cool air between rooms using a fan, or by finding alternative means to cool the surrounding rooms.

Long answer

An air conditioner is a machine that exploits the physical properties of a chemical called a refrigerant to concentrate and move heat energy between two heat exchangers. The heat exchangers allow transfer of heat energy between fluids, like air or water.

Most portable air conditioners are designed to collect heat from the air inside a room and dump that waste heat energy into a stream of air that is then expelled outside, so the heat can disperse. They are already somewhat inefficient at doing this, compared to other types of air conditioners.

Even if you found a way to transfer the heat from the exhaust air into a container of water, that heat energy would simply leak back into the room from which it was removed. This is similar to leaving a refrigerator open and assuming the room will cool down - it doesn't, because the heat being removed from the interior isn't being released somewhere else.


So we know that the air conditioner won't work as you described, so here are some alternatives:

  • If you'd still like to use the portable air conditioner in the kitchen, see if you can cut a hole and install an exhaust vent that's the same size as the outlet hose. This is easier than installing a window and gives you a way to remove the heated air, but you'll still need to mind the condensation that collects in the machine
  • A more expensive and intensive option is to install a ductless mini-split unit. These separate the heat exchangers into indoor and outdoor units, requiring only a small hole to pass wiring and condensate and coolant hoses through. The installation is much more involved, though.

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, 2016 at 18:15
  • 1
    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, 2016 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, 2016 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, 2016 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). Aug 3, 2016 at 19:11

You could invent a water cooled unit that connects to your water faucet and then sends the warm water down the drain or outside. It would work fine, as well as a window AC or dual pipe portable AC, except for the high water bill.

To do what you want to do you would have to have some kind of big radiator that air flows through that you can hook up to the AC vent, like an intercooler from a turbo changed engine, and then put that in the bath tub with some water flowing to keep the bath tub cool.

Better yet invent one that uses closed loop water cooling that has radiator and fan that you set outside.


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.

If it's a decent power AC, it will output at least 2kW thermal power in the exhaust. Rounding a bit, that will increase the temperature of 1 liter of water by 0.5°C per second, so it will heat a 20 liters bucket from 15°C to 50C in about 22 minutes. So you would need a very large quantity of water.

Also these ACs have a huge airflow, I mean they really blow, so it is not obvious how you would make the air meet the water without the whole thing turning into an omnidirectional shower.

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.

Yes, it won't work. Also due to the huge airflow, the pipes have to be quite short.

You can put the AC near the window and aim the cold air jet to where you want though.

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