Comment on The interior of your house is hot, the exterior cool. What would the most efficient orientation be for a box fan? Pushing hot air out of a window or pulling cool air in through it?

vivavideri@lemmy.world ⁨1⁩ ⁨year⁩ ago

• franglais@lemm.ee ⁨1⁩ ⁨year⁩ ago

  This is the wrong application, noctua are looking for static pressure, what OP wants is to maximise airflow. Mathias wandel has some pertinent videos on the subject, the ideal is a large fan about a metre or two away from the window, depending on the size of the fan, blowing hot air outside.

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  • sneekee_snek_17@lemmy.world ⁨1⁩ ⁨year⁩ ago

    Why so far from the window?

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    • SzethFriendOfNimi@lemmy.world ⁨1⁩ ⁨year⁩ ago

      I think you get the benefit of the airflow pulling in air along its edge to push out with it.

      Like pushing a bunch of water with a broom removes not only the water in front of the broom but also more water due to surface tension and inertia

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      • ShepherdPie@midwest.social ⁨1⁩ ⁨year⁩ ago

        It’s called the venturi effect.

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      • kakes@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

        It’s called the linguini effect.

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      • sneekee_snek_17@lemmy.world ⁨1⁩ ⁨year⁩ ago

        Ohhhhhh the bernoulli effect?

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      • tiefling@lemmy.blahaj.zone ⁨1⁩ ⁨year⁩ ago

        Good ole vermicelli effect

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      • franglais@lemm.ee ⁨1⁩ ⁨year⁩ ago

        In this case it’s called the brunelli effect

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      • altima_neo@lemmy.zip ⁨1⁩ ⁨year⁩ ago

        Ah yeah, the Dom Mazetti effect

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      • Chee_Koala@lemmy.world ⁨1⁩ ⁨year⁩ ago

        Its called the Chimichurri effect

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      • Hupf@feddit.de ⁨1⁩ ⁨year⁩ ago

        The Bozzetto effect?

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      • Peppycito@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

        It’s called the kimchi effect

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      • KillerTofu@lemmy.world ⁨1⁩ ⁨year⁩ ago

        It’s the butterfly effect.

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      • Feathercrown@lemmy.world ⁨1⁩ ⁨year⁩ ago

        Oh yeah the bruscietta effect

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    • pmk@lemmy.sdf.org ⁨1⁩ ⁨year⁩ ago

      It creates an effect where surrounding air is pulled with the stream due to the Bernoulli effect. It’s the same thing that pulls shower curtains in when you shower. If the fan is a bit inside the window, surrounding indoor air gets pulled into the stream, moving more air out in total.

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    • NeoNachtwaechter@lemmy.world ⁨1⁩ ⁨year⁩ ago

      A fan creates kinda long “channel” in front of it and behind it, where the air is moving rather fast (at the speed that the fan creates). Imagine the narrow beam of light from a flashlight. You want that channel to go right through the window to have a good amount of air flowing.

      I don’t know that you need to keep a distance from the window. I think 1-2m is just more practical than having the fan right inside the window frame.

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      • subignition@fedia.io ⁨1⁩ ⁨year⁩ ago

        do you happen to know whether this is significantly different for a blower-style fan that has its air intake on one side? for example

        https://lasko.com/collections/air-movers-blowers/products/lasko-12-pivoting-pro-high-velocity-utility-blower-fan-with-3-speeds-u12104-gray

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    • Hacksaw@lemmy.ca ⁨1⁩ ⁨year⁩ ago

      Most of the replies are correct overall. But Mattias Wandel had identified another important factor. Fans don’t just “stuck from the back” and blow out the front. They sort of suck from everywhere including the edges. This means that if you’re putting a fan right up against the window blowing in you’re sucking some room air as well. If you’re putting the fan right up against the window blowing out, some of the air you’re blowing out comes from outside in the first place.

      The ideal is then to blow out from 2-5ft away. This way all the air that’s blown is room air, and it’s all blown out. The venturi effect plays a small part. The Bernoulli effect? Equations? Explains why the air stays in a “tube” for a few feet away from the fan. Technically also explains the venturi effect… Everything is Bernoulli…

      www.youtube.com/watch?v=1L2ef1CP-yw

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      • sneekee_snek_17@lemmy.world ⁨1⁩ ⁨year⁩ ago

        This was a wonderful comment to read and video to watch, thank you

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    • traches@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

      Same reason why blowing on your hand close to your mouth is warm, but farther away is cool.

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  • HelixDab2@lemm.ee ⁨1⁩ ⁨year⁩ ago

    Can you explain that? With one fan pushing air in, and one fan pushing air out, you should be achieving higher airflow than you would with a single fan pushing air either in or out.

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