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Should I close the door when running AC in fan mode

  1. Jun 13, 2017 #1
    I have a 3x3.5 (meters) room with a bathroom of approximately 1.5 x 2.
    I want to know whether to close the door or not, If I running Fan Mode.
    There is wall in front of my door, about 60 cm,

    My assumption: Fan mode only circulate the air, If I open the door, I'll bring outside air in, which is better than just inside air
  2. jcsd
  3. Jun 13, 2017 #2
    I have not heard before of a fan mode in a bathroom.
    In my own bathroom there is an extractor fan; the fan goes on when the light is on,
    (that is, somebody is using the bathroom)
    Opening a door or closing it will not make a lot of difference to the flow of air.
    Air is gases; gases flow from higher pressure to lower pressure and solid objects usually don't stop it. gas finds a way around it.
    Last edited: Jun 13, 2017
  4. Jun 14, 2017 #3


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    There are some things that aren't clear to me, but I'll give this a shot:
    1. Yes, "fan mode" just re-circulates. It does not bring in outside air.
    2. What door are you opening? Door to outside or door to bathroom. If it is the door to the bathroom, I don't see why outside air will come in. If it is the door to outside, sure, air will come in, but your system's "fan mode" won't affect that.
    3. Sometimes bringing in outside air is useful and sometimes it isn't.
  5. Jun 14, 2017 #4


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    Your OP doesn't mention temperature or humidity at all (inside or out) so really impossible to know what you are trying to achieve.

    Where I live opening an outside door is currently a bad idea, but in 5-6 hours it will be a fabulous idea, I can't wait.
  6. Jun 14, 2017 #5
    Okay, I'll try to explain a little bit more of the room,
    - There are no windows in the room
    - What I open is the door to the outside
    - Not really "outside (like open field)", because the room is in the (boarding) house.
    - In front of that door is a wall, on the right about 20cm, is a window.

    Actually I am curious to know what are the benefits for opening the door and closing the door when running on "Fan Mode".

    Just want to know what will happen in 5-6 hours? :)
  7. Jun 15, 2017 #6


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    The sun sets and it gets cooler outside than inside.
  8. Jun 16, 2017 #7
    If you want to go for an overkill solution, you can try and simulate it with SimScale. There are examples that are similar to yours like the airflow in an office space.

    You can get sign up and create a free account and try things.
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