I'm looking for a portable air conditioner that can be moved from room to room. But the key thing I want is one that does not use a condensation tank. I know they exist because I have seen one. It diverted the cool side (refrigerant evaporator) condensation to the hot side (refrigerant condensor) and evaporated it into the heat exhaust air flow. I don't know if it used gravity or a pump to accomplish that. If the hot side is on the bottom it seems gravity could do this job to get the condensation from the cool fins to the hot fins.

Here's the problem I'm having with this search. What terminology is used to define this? I thought it would be "evaporative". But I'm seeing "evaporative" used for something different which requires chilled water to be added to the unit (definitely not what I want). Apparently it is this type (which I do not want): http://en.wikipedia.org/wiki/Evaporative_cooler

I searched for "tankless" but very little matched (and all too large, anyway).

So what standard term should be searched for, or asked of sales people, to get to the right type of air conditioner (refrigeration type, with condensation from the cool side fed to the hot side to evaporate through the heat exhaust tube (for portable unit where the tube(s) would go typically out a window)?

The specifications for many of these portable air conditioners list the tank size. And it looks like some have rather large tanks. Clearly these are not the ones to get. But with virtually all retailers regularly omitting many crucial specification on just about everything, I cannot trust the lack of a tank size specification as an indication that it evaporates the condensate.

  • An AC unit is a giant dehumidifier. Even with standard window units, where there's a lot of heat and a lot of air movement, there's still a lot of water. I can't imagine the hot air duct, alone, would be enough to get rid of all the moisture.
    – DA01
    Commented May 27, 2012 at 21:32
  • There is more heat at the refrigeration condenser fins than was released by the condensation of water on the refrigeration evaporator fins. So, in theory there is enough heat to evaporate the water that was condensed. The only limitation I can see is that the (now moist) heat exhaust through the tube out to the window would re-condense the water vapor on its insides where exposed to the cooled room air. The unit I did see was doing a very good job of this because it had no drain line or tank. I just wish I could remember the make and model from seeing it 12 years ago.
    – Skaperen
    Commented May 27, 2012 at 22:24
  • Keep in mind the hot air side is also often quite humid to start with, so it can only hold so much more water. But I'm no scientist, so such a thing may very well exist. I'll be watching the answers too!
    – DA01
    Commented May 28, 2012 at 0:37
  • Since it is circulating outside air, which is generally hot and typically humid (at least where I live), of course that will be coming in through the intake hose. But heat is added by the condenser side. This is more heat than given off by water condensing on the evaporator side, by including room heat as well. I don't have numbers nor do I know the formulas to work that out. But it seems plausible that there is enough heat to expel the water as vapor. I know the unit I saw does work. And I think it would make the system more efficient by being an evaporative system on the hot side.
    – Skaperen
    Commented May 28, 2012 at 5:25
  • Consider the opposite design where the waste heat is disposed in the condensate water. Since the heat released by condensing the water is just part of the heat to be disposed, this design cannot work because it would boil off the water. I think the design of boiling off the condensed water should be added to all such units to make the refrigerant condenser more efficient at releasing heat. Now I am wondering where the condensate in my kitchen refrigerator is going.
    – Skaperen
    Commented May 30, 2012 at 22:01


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