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Air conditioning unit with slightly open window

  1. Jan 7, 2017 #1
    Hi all,

    I want to buy an air conditioning unit while they're cheap and I know you're not meant to have any windows open. I have strange windows so cannot use the fishnet attachment, long story short, if I hang the hose out of the window and just try to close the window as much as possible, will the air conditioner still cool the air?

    Everywhere I read online it says closing windows is extremely important.
  2. jcsd
  3. Jan 7, 2017 #2

    Vanadium 50

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    Sure, it will cool the air. And then the cold inside air goes right out and the hot outside air comes right back in, leaving you with a hot room.
  4. Jan 7, 2017 #3
    Depending on where you buy it, I don't think you're going to save much (or any) money buying an AC now rather than, say, in the spring. It's only a good idea to buy one off season because, when the heat wave comes, the local Home Depot may sell out of units and then your in for bad times. I've been there. Took 10 days to get one on order with 90+ temperature.

    Plus, it looks as though you want to buy a portable AC (one with the hose). I would advise against this unless that's your only option. They're often up to twice as expensive as the window mounted models and they don't work nearly as good. I bought a 12,000 BTU portable and it didn't work as well as a 6000 BTU window mounted unit I got.

    Finally, I would recommend getting an 8000 BTU window-mounted unit (or two or more depending on the size of your house) rather than a 5 or 6000 BTU unit even if you a have a small bedroom. It's only maybe another 50-100 bucks but you're going to love how cold you can make your room when it's like a furnace when you walk out of it. Plus, if you take care of it, you can have it for a lifetime. So the extra 50 bucks is well spent.

    Yeah, as Vanadium 50 said, that's kind of the whole idea of the air conditioner, to keep the windows closed, just like keeping the refrigerator door closed :redface:
  5. Jan 7, 2017 #4
    Even if the window is open just a little way?

    I live in an apartment so I'll have to check out the window mounted ones but I was hoping for a portable AC unit. I'll give it some thought, thanks.
  6. Jan 7, 2017 #5


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    There are other ways to close a window opening.
    Stuff some foam in the opening, cover it with tape, or use a polyurethane foam sealant (maybe not in a rental), then you can reduce this effect:
  7. Jan 7, 2017 #6

    Vanadium 50

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    The more it's open, the worse it gets. But it's clear you aren't looking for information., You're looking for validation, so go ahead and do whatever the heck you want.
  8. Jan 7, 2017 #7
    I said I'll look into the window mounted one... I just wanted to make it clear that my windows are not going to be wide open letting all the air out and was just making sure you knew the window would only be open a tiny bit.
  9. Jan 7, 2017 #8


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    Yes, it will still cool the air.
    Yes, closing the window is extremely important.
  10. Jan 7, 2017 #9
    This thread is funny. I don't understand why if the window is open only a "tiny bit" that it cannot be plugged up with something, as BillTre suggested.
  11. Jan 8, 2017 #10


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    I don't get why you make fun of the OP. For obvious reasons you can't stick the hose out of the window without leaving a gap through which the hose goes - so the window can't be completely closed, I assume that's what OP means. To make things worse if it is a window like the ones used in most of the Europe, with hinges on a side (and we don't know what kind of a window OP has, other than they are not typical) it is not easy to plug the gap, as it goes around three sides of the window.

    In this context problem (and the questions) looks perfectly valid and reasonable to me.
  12. Jan 8, 2017 #11
    Quite a big design flaw in such models unless some drilling is standard requirement. Easier if the hose is thin enough to go through the window frame than the wall.
  13. Jan 8, 2017 #12


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    Try to ensure the seal is as good as possible.

    The first law of thermodynamics states that if you have 1000 W air conditioner in a closed system (one without windows at all [like an air conditioner sitting in the middle of your living room]) it will act essentially the same as a 1000 W space heater. It will only heat things up. There is nothing in this universe -- nothing at all -- that can continually cool stuff, overall, in a cyclical process. You can heat stuff up all you want, but you can't cool stuff without heating something else up even more.

    If you want to cool things down you need to isolate the heat sink: keeping that window closed is crucial.
    Last edited: Jan 8, 2017
  14. Jan 8, 2017 #13


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    Baffle plate .
  15. Jan 8, 2017 #14
    I'll look into getting some foam and trying to block the window opening then.

    I really only wanted to know if the AC would still work to some degree with a slightly open window. Cheers for the tips.
  16. Jan 8, 2017 #15
    Foam around the hose and then use clay or playdough to finish the fine curves around it. It is really not an incredibly difficult thing. Granted, there are certainly good ways and bad ways to do it, but you can definitely rig something up to minimize hot air getting in.

    Even with windows that open like doors you can plug it up for the most part. Just depends on how creative you want to get.

    Given that I tend to be rather haphazard with my arts and crafts, were it me I'd be using duct tape, plastic bags, foam, blankets, clay and probably wads of paper too. Basically anything that would help, and it would look pretty stupid, but by the end pretty much all of it would be plugged up.
  17. Jan 8, 2017 #16


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    If your air conditioner works by pushing hot air out of the building through a hose, then an equal amount of air from outside will be drawn back into the building to replace the air that has been removed. That is unavoidable, no matter much you try to seal up gaps to prevent air entering. Air has to enter from somewhere.

    If your air conditioner works with two hoses, one expelling hot air and the other drawing in cooler air, then it might work, if it's designed properly.
  18. Jan 8, 2017 #17


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    Not that it is ok to make fun, but I think people were reacting to the fact that that is a really, really, really, really easy problem to solve. So why not just solve it?

    I'd be willing to be the instruction manual points out just how important it is.
  19. Jan 8, 2017 #18
    What's your ambient outside temp where you nest?

    If your up in the north pole you'll be fine!

    Here in Arizona a small crack feels like a blowtorch in tha' summertime! :oldshy:
  20. Jan 8, 2017 #19
    I once had a window unit that I didn't even put in a window (when I was living in a garage). The net temperature of the room didn't get colder, but that air conditioner was pointed directly at me all the time, and by golly it kept me cool :). Of course I had it rigged to drain water into a plastic bin, which I had to periodically empty. But while the room was not cool, I was. XD
  21. Jan 9, 2017 #20

    Fervent Freyja

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    You must not have a pane that can shut (close) onto the unit in order to keep it from falling out, is that what you meant?
  22. Jan 9, 2017 #21
    I found one in tha' dump once... It didn't have a manual. :oldgrumpy::sorry:
  23. Jan 9, 2017 #22
    I did that once..... Then my mom kicked me out...:smile:

    LOL... I wudda' dug a hole, drain tha' H2O in it and made a fish pond!
    Yummy,,, fish sticks! :redface:
  24. Jan 9, 2017 #23
    Ahaha so you like fish sticks, huh? *insert South Park joke*
  25. Jan 9, 2017 #24
    lol... :smile:

    Lemmie axed ask ya' something Battemage.... Is this lounge place ok to just blab? I don't wanna' to get in trouble.. Because I really like this place..I really like all science.. especially physics.

    Also I don't wanna' derail our OP friend... I just don't now where to go to blab to other physics freaks, except right here in the physics lounge.. ! :sorry::redface::oldsmile:
  26. Jan 10, 2017 #25
    I do not know... but I do know even in the serious forums an occassional humorous quip is tolerated, so long as it doesn't distract.

    In general discussion? Not sure. I do know that if things got too far off topic the mods are more likely to delete posts or close threads than outright banning people. Usually it's for psuedoscience and a complete unwillingness to adhere to the rules and warnings regarding that that get people banned.

    This is a pretty reasonable forum and as long as you aren't coming here with some baseless agenda there shouldn't be an issue. People are given fair warning here, based on my experience.
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