I have a portable air conditioner, but I don't have a window in my room. I'm only gonna be here for about 2 more weeks, but the temperature is in the 80s/90s, and I'm very sensitive to the heat that it's affecting my sleep, so I'm trying to find a temporary solution. a

There is some sort of vent on the wall with a casing, but it seems I can't remove the casing, otherwise, I think I could simply just remove it, and stick the tube of the portable AC in there, and that should work?

Would it work if I try to vent the hot air out of my room through my door? I would leave the door cracked open slightly (just enough to put the tube through), but I don't know how well this'll work, since hot air will just come in through the crack. I'm not well versed enough with heat transfer analysis to know if the net heat flux coming in is positive or negative with this idea.

Any suggestions would be greatly appreciated!

I'm not too concerned about efficiency as I will only be here temporarily. The room right now is about 85 degrees, if I can get it down to 70-75, I would be happy.

  • Pumping it into a vent you do not the purpose for is usually a bad idea. If the door is to the outside, and not into someones living area, could place a blanket or something around the opening.
    – crip659
    Jun 6, 2021 at 0:30
  • @crip659 No, the door is to the hallway, but I am the only person living here, so I don't really care that the rest of the place gets hot unless there's some safety issue.
    – anonuser01
    Jun 6, 2021 at 0:32
  • You seem to have a handle on the thermodynamic issues... I trust this is old news to you? You might be better off figuring out why your room is getting warm when it doesn't even have an outside wall. Jun 6, 2021 at 6:36

1 Answer 1


A "single hose" portable AC will take in room air, return some of it cooled, and exhaust some of it heated.

Usually the heated exhaust is led to the outside.

The conditioned space will take-in from cracks and other openings, usually the room door, to make up for the exhausted air, in equal amounts, i.e. equal flow.

The AC can cool the room as long as the replacement air is cooler than the exhaust. The required differential is a significant factor in the AC efficiency.

In your case it seems that the replacement air comes from the same hallway that you are exhausting into.

This could work if the hallway is large enough and/or has enough ventilation so as to maintain a relatively constant temperature despite the hot exhaust from your AC feeding into.

Try it out:

  • make sure the hallways is well vented and as open as possible by opening other doors into others spaces
  • extend the exhaust so it leads as far away from your door as possible.
  • no need to block the rest of the door, it's your replacement intake anyway

If you can reach the exhaust into a different room that has a window or perhaps into a bathroom with an exhaust fan, that would be great. It's ok to extend the hose a bit. Use rigid and/or flexible tubing of the same or preferably a larger diameter, and connect it with duct tape and/or a hose clamp.

  • I think I can get the vent hose to reach the bathroom, which has a vent on the ceiling. The hose won't reach the ceiling of the bathroom, but would it be a good idea to just leave it sitting in the bathroom instead of the hallway since presumably the bathroom would be more ventilated due to the ventilator in there?
    – anonuser01
    Jun 6, 2021 at 1:22
  • If it has a ventilator, run it the whole time. That would be perfect.
    – P2000
    Jun 6, 2021 at 1:24
  • I'm a bit new to these things, but is a "ventilator" in the bathroom just that fan thing on the ceiling that circulates air?
    – anonuser01
    Jun 6, 2021 at 1:26
  • If it has a grill/register and pulls the air out, then that's what you want. If it's just a blade stirring the air, then there's no point. To determine whether whatever is behind the grill works, hold a napkin close to it and see if it gets pulled to it. You can usually also feel the airflow with wet hands. So check this. There could be a fan right behind the grill, which you will hear, or somewhere far away on the roof, and then you won't hear it, so it could be silent but still work.
    – P2000
    Jun 6, 2021 at 1:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.