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July 26, 2015 9:56 AM   Subscribe

How to build an air conditioner in under 15 minutes. How to build a slightly fancier portable version.

*Okay, technically they're air coolers, but still.
posted by Room 641-A (26 comments total) 14 users marked this as a favorite
 
I present to you, FigJam's $30 Swamp Cooler Bucket, and the epic 109+ page forum thread on all things swamp cooling.
posted by Freen at 10:02 AM on July 26, 2015 [2 favorites]


If you really want something cool, try it with an ultrasonic fogging device in the reservoir, like one of these.

The ten-head pool models can easily fill a room with fog, using only a small 4” fan to blow it…try it, it works great!
posted by littlejohnnyjewel at 10:33 AM on July 26, 2015


Swamp coolers don't work here because the humidity is already 110%.
posted by Bringer Tom at 10:43 AM on July 26, 2015 [11 favorites]


Yea, if only it were so easy for folks living in the swamp or, hell, anywhere the humidity is high for that matter.

Cool background music though. *twee deedle de deeee, ba da bump bump, cha*
posted by RolandOfEld at 10:57 AM on July 26, 2015


I present to you, FigJam's $30 Swamp Cooler Bucket,

What I liked about these is that there's no pump, no tubing/running water, copper, etc. so maybe people who were hesitant to try making one would find this easier. But yeah, there are definitely more elaborate versions out there for people looking for a more serious project.
posted by Room 641-A at 11:04 AM on July 26, 2015


Yes, swamp coolers are most efficient in dry climates. If you try to use one when it's humid, it'll cool less and you'll get really sticky.

I live in a semi arid climate, and I keep a chart like the one on this page next to my cooler. The rare times when it's hot and humid, the cooler just makes it worse.

It's pretty sweet, though, when it does work. It's very effective in dry weather, and it's much less expensive and more energy efficient than air conditioning. It's more pleasant than air conditioning, too, because you're supposed to open up windows and circulate the air for best results.
posted by ernielundquist at 11:07 AM on July 26, 2015 [2 favorites]


Note that the heat generated in creating the ice will be greater than the cooling produced by this device. If you make ice in your freezer, then use that ice in this cooler, the net result will be to make your apartment warmer-- the ice needs to be created outside the space you're trying to cool.
posted by justkevin at 11:07 AM on July 26, 2015 [9 favorites]


Swamp coolers don't work here because the humidity is already 110%.

If you use frozen bottles of water, then water won't escape the system and the humidity won't matter. It'll be slower, but it'll also save water.
posted by JHarris at 11:58 AM on July 26, 2015


I'm in a dry climate with a refrigerant AC. Always wonder if I should set up a mister near the outdoor coils. Would the humidity increase it's efficiency?
posted by five fresh fish at 12:00 PM on July 26, 2015


If you use those gel ice packs, would you get more cooling time? I think they have a higher thermal capacity, so they should be capable of storing more heat before melting.
posted by five fresh fish at 12:01 PM on July 26, 2015


To match a 110v 4000 BTU window or portable AC unit you will need about 20 gallons of ice every hour of operation.
posted by humanfont at 12:04 PM on July 26, 2015 [3 favorites]


Good ol swamp fans. I used to work in a position that had around 8 people working in a building over weekends that normally housed around 200. Someone kind of forgot about us always being there on weekends and decided to save money by turning off the AC on the weekends since no one was there (they thought). This decision was made mid summer in the South of the USA and it reached around 90 inside the building.

So we scrounged up the hardware required and made about 4 of these bad boys. Pointed them at our little circle of worker bees and viola, we didn't feel the need to murder anyone at the moment.

Then we'd sort of forget that it was still technically 90 outside our square, would run down to the breakroom or to the bathroom, and BAM like walking into a mouth.
posted by Twain Device at 12:10 PM on July 26, 2015 [1 favorite]


My great aunt had a swamp cooler for a time back in the 70s. In Arkansas. Being in far northwest Arkansas it didn't get quite as humid as it did farther south, so it managed to get the house down to the low 80s, which is a damn sight better than 95. I think that living up on top of a mountain also somehow helped with the humidity a bit.
posted by wierdo at 12:37 PM on July 26, 2015


I made one of these last year. Works surprisingly well. As mentioned, the energy removed from the water to freeze it has to go somewhere, but having a freezer in a shed (or even just a different room) helps a lot.

You could do something similar with a different heat dump, like a lake or swimming pool. Basically anywhere you can dump the extracted heat into, via a heat exchanger. The colder the heat dump is, the better, though.
posted by Solomon at 12:39 PM on July 26, 2015


I thought that these things worked based on heat of evaporation, not heat of fusion? Like, they basically blew hot dry air over some kind of wicking material suspended in water, and the heat lost to evaporation changed it from hot and dry to cool and moist? It does seem like pre-freezing the water would ruin the whole system, since you'd have to run a refrigeration pump to make the ice and at that point you might as well just use the pump to chill air instead (like, you know, an air conditioner). Not to mention (as justkevin has already done) that if you're making the ice inside of the space that you're trying to cool, you're going to end up with a net temperature increase since cooling things with refrigeration is much less than 100% efficient and all the waste goes pretty much straight to heat.
posted by Anticipation Of A New Lover's Arrival, The at 1:51 PM on July 26, 2015 [2 favorites]


I don't know if using ice ruins it, but it's not necessary. Most store boughten swamp coolers, like the one I have, just hook up to a water line.

I've tried dumping some ice into the reservoir before, but I didn't notice much if any difference in cooling. This site seems to agree that the effect is negligible at best.
posted by ernielundquist at 2:08 PM on July 26, 2015


To match a 110v 4000 BTU window or portable AC unit you will need about 20 gallons of ice every hour of operation.

Your numbers are a little off. A pound of ice absorbs 143 BTU of heat when melting. So to match a 4000 BTU per hour air conditioner (typical small room size), you would need 28 pounds of ice per hour or about 3.7 gallons. That's still a lot of ice.

Let's also look at cost. 28 pounds of ice costs about $3 retail, conservatively. The air conditioner uses about 500 watts or about a nickel an hour. Three dollars an hour for this device vs a nickel an hour for the air conditioner.

Given that you can buy a room conditioner for about $120, there is no point to this Rube Goldberg machine unless you do not have access to electricity or ice is almost free.

What this is saying is that it is about 60 times more efficient to bring electricity into your home for cooling than to bring ice into your home for cooling.
posted by JackFlash at 2:17 PM on July 26, 2015 [11 favorites]


Or that I need to invent a system to pipe pellets of ice into people's homes.
posted by VTX at 2:32 PM on July 26, 2015 [1 favorite]


Or that I need to invent a system to pipe pellets of ice into people's homes.

That's effectively what a power grid is -- a virtual machine for piping ice into people's homes efficiently.
posted by JackFlash at 2:38 PM on July 26, 2015 [2 favorites]


That's effectively what a power grid is -- a virtual machine for piping ice into people's homes efficiently.

Akin to the real machine in The Diamond Age that cools itself by getting microscopic ice pellets off the Feed and outputting warm water.

†: Well, fictional
posted by cardioid at 3:52 PM on July 26, 2015 [1 favorite]


I would not have assumed that those little coolers were meant to replace a regular cooling system, but for short term uses like camping or power outages, and for brief respite for those who don't have and maybe can't afford something else.

(Also, on second thought, I'm not sure they're really evaporative coolers at all, as I was assuming. It looks like maybe they just blow cold air out.)
posted by ernielundquist at 4:11 PM on July 26, 2015 [1 favorite]


Given that you can buy a room conditioner for about $120, there is no point to this Rube Goldberg machine unless you do not have access to electricity or ice is almost free.

Good point. The one remaining advantage of the Rube G machine is that it is way quieter than a room air conditioner.
posted by storybored at 10:01 PM on July 26, 2015


On second thought why not skip the cooler bizness and just put a couple of frozen water bottles in front of the fan?
posted by storybored at 10:12 PM on July 26, 2015


Given that you can buy a room conditioner for about $120, there is no point to this Rube Goldberg machine unless you do not have access to electricity or ice is almost free.

The main reason i've seen people build these is either to use them in places where electricity isn't available or hard to come by in any decent capacity(IE, burning man) or when they had almost all the pieces, if not all of them already and were cash poor but had a wealth of free time... IE, students.

They work OK, but i never understood the logic of building them when the local thrift store seems to almost always have swamp coolers.

The main thing i always had against these was... why would i want to add humidity when it's hot out? The lack of humidity is what's making this shit tolerable! Unless i'm in the literal desert i just despise that concept, especially indoors.
posted by emptythought at 3:29 PM on July 27, 2015


Well, I've only ever heard of these things (evaporative coolers, swamp coolers) being used as a serious alternative to AC in places like Arizona and New Mexico, i.e. the literal desert. If you're somewhere where you might want both an air conditioner and a humidifier to maintain comfort, basically.

Swamp coolers work best in places like that anyway, and can be much cheaper to run than air conditioners provided you aren't running them on ice which is something I'd never heard of before this thread.
posted by Anticipation Of A New Lover's Arrival, The at 5:38 PM on July 27, 2015


The units in the post aren't really swamp coolers, though. I haven't seen one in person, but it looks like they're just running the fan over the cold air emitted by the melting ice, whereas an evaporative cooler uses this process to cool the air, intentionally introducing water into the air. Evaporative coolers do add quite a bit of humidity, but these devices don't really look like they would.

As swamp coolers go, though, I'm in the Denver area, which is not a desert, but semi arid, and there are maybe two days a year where it's hot and humid to the point that the swamp cooler doesn't bring it down to a comfortable temperature. And two kind of uncomfortable days isn't that big a deal when you take into account the savings (money and energy).

Heh. Maybe I should make one of those coolers to use on those days.
posted by ernielundquist at 8:55 PM on July 27, 2015 [1 favorite]


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