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hmmm (lemmy.world)
submitted 4 months ago by to c/hmmm@lemmy.world
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[–] 49 points 4 months ago (26 children)

I actually set up the opposite for my system - exhaust carried straight out the window so that the AC wouldn’t have to counteract PC heat

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  • [–] 14 points 4 months ago* (21 children)

    If you don't have a way to counteract the negative pressure you're just drawing in warm outside air from somewhere else, which kinda defeats the purpose. I'd be surprised if there's a measurable difference from simply allowing it to exhaust into the room.

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  • [–] 5 points 4 months ago (1 child)

    It depends how hot it is outside.

    If it's 110 F outside, sure. It might be a bad idea... Maybe. Depends how hot that pc air is.

    If he's exhausting 115 F out the window, however, and the negative pressure is drawing in 100 F, then he's cooling his pc and his home.

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  • [–] 3 points 4 months ago (18 children)

    Not sure I understand what you mean?

    Purpose is to get the PC’s hot air straight out in order to avoid warming the room. In addition to forced air from the exhaust and radiator fans, I added an inline fan to help it on its way out the window.

    The PC was already set up for negative pressure and was still intaking air from the room. Goal was not to reduce PC temps, but to keep the room comfortable for humans while avoiding additional energy consumption by the air conditioner.

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  • [–] 14 points 4 months ago (12 children)

    They're talking about your whole house - by venting the PC to the outside, you're creating negative pressure in your house. Even with all the windows and doors closed, this will draw in outside air from somewhere.

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  • [–] 4 points 4 months ago (3 children)

    But isn't the easiest point of entry the AC unit?

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  • [–] 15 points 4 months ago* (1 child)

    The ac isn't taking air in from outside, it's two different (and isolated) air routes. It takes in air from inside the house, cools it, and puts it back into the house. The outside air loop takes in outside air, heats it, and dumps it back outside.

    These two loops never mix, at least on a residential system. Commercial is a different beast that does use external intakes.

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  • [–] 7 points 4 months ago (7 children)

    While that might technically be true, in practice that volume of air is so small it’s inconsequential. There’s already a floor AC unit working by a similar mechanism - it exhausts hot air out the same window gap as the PC.

    Practically speaking, this setup made a massive difference in my apartment’s temperatures during the hotter months. I can even use it without AC when it’s balmy, maintaining a comfortable temperature instead of baking in my office.

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  • [–] 8 points 4 months ago (6 children)

    ACs do not transfer air from indoors to outdoors. Unless you have one of those single-hose "portable" units, which do not work very well, for the same reason. The effectiveness is going to be based on the temperature of the "replacement" air. If it is meaningfully cooler than the air you're exhausting it may work, but at that point why not drop the AC and just cool passively.

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  • [–] 6 points 4 months ago (1 child)

    Using a portable -one hose- AC give me about 5 degrees delta in half my small house during the EU heatwave, in my case improving on passive cooling by multiples, so your last sentence just sound like ' I've never felt the effects of portable AC' to me. probably pretty common in the US, but EU houses often dont come with AC preinstalled.

    I get that it's a dumb system, and I even knew before I bought this one hose monstrosity, but it's what is available to us here right now, and the fact that a split ac or window ac or 2 hose airco system (there was 1 model available to me locally, and it was sold out) is way more efficient doesn't magically make the one hose version work bad. It still uses the compression cycle for refrigeration, which is very powerful even when used inefficiently.

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  • [–] 1 point 4 months ago (1 child)

    I see portable ACs with a single hose as single room ACs. The room with the AC is cooling and pulling air from the rest of the house. That air is being replaced by outside air in those rooms.

    But yeah, passive cooling is always good to do. Even with the best AC.

    I have added a second hose to my portable single hose AC. Just a hose that is "hanging" against the input part of the AC so if there is negative pressure, the air will get sucked in directly into the AC.

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  • [–] 2 points 4 months ago

    You can definitely work it to your advantage in some situations. Last time I used one it was in an old apartment building which had AC only in the common hallways. Our unit's giant windows and about 10,000 coats of paint on everything made the exterior walls functionally airtight compared to everything internal to the building, so creating some negative pressure pulled in "free" conditioned air from the hallway. The only downside was turning our apartment into a sink for everyone else's cigarette smoke and cooking smells lmao

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  • [–] 1 point 4 months ago*

    What a weird statement to keep repeating when it has such a big exception. "ACs don't do X unless its one of the most common types of AC."

    ACs clearly do X, just not most of them. A lot of them explicitly do exchange air with the outside, because single hose portable types are widely used everywhere. They aren't ideal, but they are very common and are indeed "AC."

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  • [–] 6 points 4 months ago

    By exhausting the PC outdoors you're creating lower pressure inside the room/house. Outside air will seep in from somewhere else. The question then becomes where is that air coming from and is it meaningfully cooler than the hot air coming out of the PC.

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  • [–] 2 points 4 months ago (2 children)

    Are you able to share what inline fan you used?

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  • [–] 1 point 4 months ago

    What if the warm air coming out of the computer is still cooler than ambient? If the AC output volume is sufficient and you aren't melting lava inside your computer it's entirely plausible that it's not greater than ambient and technically cooling the room.

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