Homebrew Air Conditioning for Under $25

inkey string writes "Summer has arrived, and I've been busy slowly overheating in my student house without central air. I decided to put my thermodynamics classes to work however, and produced this ~24$ homebrew air conditioner. It'll cool a room to a comfortable level in 15-20 mins, and will run for a few hours on a garbage pail full of water. It's cheap, environmentally friendly (just fire the waste water off to your garden), and makes a good one hour project for a quiet evening."

Its going to be hot soon

[Anonymous Coward]

I hope his server isn't in his room, because all the thermodynamics courses in the world wont teach you about slashdotting.

Re:Its going to be hot soon

[Anonymous Luddite]

>> I hope his server isn't in his room

It's actually a University of Waterloo server. I'm sure the sysadmin is gonna love this sudden DDOS.

Re:Its going to be hot soon

[PingPongBoy]

With all respect to university resource limitations, you would think they would be most proud of having their students attracting world attention, especially for something laudable.

Web pages for professors hardly get any news coverage, and these people are supposed to be at the top of the game. Surely research funding would leap to another quantum level if professors discussed on their websites how much impact or influence their research has, especially if those sites attracted page hits from large numbers

Re:Its going to be hot soon

[Anonymous Coward]

This article is so ignorant I almost took the time to create a Slashdot account to complain about it.

Re:Its going to be hot soon

[Kujila]

How can this story be slashdot-worthy if the fan isn't even running Linux!

The guy is a moron

[tangledweb]

I think my way is much more efficient and more environmentally friendly. I just hooked my freezer up to my perpetual motion machine and leave the door open. Infinite cold air, and no puddle of wasted ice water outside my window.

And you can place it...

[peter_gzowski]

...right next to your webserver.

Re:And you can place it...

[Tackhead]

> ...right next to your webserver.

By placing the garbage pail full of water in your garden, you ensure that within five minutes of the link going live on Slashdot, you'll have several gallons of piping-hot vegetable soup!

Re:And you can place it...

[Seumas]

And with the money he saved, he can finally afford a maid.

Air Conditioning for $1500/month

[Geekboy(Wizard)]

Move to San Francisco.

Today it hit 70F, and the news stations are talking about "the heatwave of 2005".

Re:Air Conditioning for $1500/month

[failure-man]

Whiny bastard Californians . . . .

I repeat my assertion that since 31 Octobher, 1995 (the last Oingo Boingo show) the state has had no redeeming value.

Re:Air Conditioning for $1500/month

[Anonymous Coward]

I repeat my assertion that since 31 Octobher, 1995 (the last Oingo Boingo show) the state has had no redeeming value.

Hey! California has amazing redeeming value. Without it, all those idiots would be living with the rest of us!

Re:Air Conditioning for $1500/month

[Anonymous Coward]

You misspelled Texas

Re:Air Conditioning for $1500/month

[lostchicken]

Shit. As a native Texan living in California, I feel I must object to one of these insults. Unfortunately, I can't quite decide which one isn't true...

Re:Air Conditioning for $1500/month

[MrAnnoyanceToYou]

Californians buy our water, we don't mind.
Californians raise our power rates by buying ours, we don't mind.
Californians make more money, we don't mind.
Californians drive up here and buy houses at HUGE prices, we don't mind.
Californians steal our nice Oregon springs leaving us more drenched than usual, we want better environmental laws or blood.

Re:Air Conditioning for $1500/month

[jdray]

Actually, the prices Californians pay for power offsets the cost to deliver electricity to customers in the Northwest. I'm reminded of the slogan at Chilkoot Charlie's in Anchorage: "We cheat the other guys and pass the savings along to you."

And, yes, I work for a power company and know how the system works.

Re:Air Conditioning for $1500/month

[kfg]

Mark Twain once famously noted that the worst winter he ever spent was his summer in San Francisco.

KFG

Re:Air Conditioning for $1500/month

[matthewn]

Mark Twain once famously noted that the worst winter he ever spent was his summer in San Francisco.

No. No he did not [snopes.com].

Re:Air Conditioning for $1500/month

[kfg]

San Francisco, Paris, whatever. :)

Ah well, if you aren't lucky you learn something new every day.

I'll make two notes though, Twain was a public speaker, and just because this particular witticism can't be found in his writtings is not actually an indication that he didn't say, and even orginate, the quote, it simply means it can be proven from the written record. There is such a thing as oral history. Many things I have orginated and said are not recorded in print, despite my post count, and the printed version of not a few things has been lost even to myself.

The second note though is my observation (and I believe that of others before me) that sooner or later every American will attribute every witticism to Twain, especially as he often used the witticisms of others, often without direct attribution since the people of his time were well aware of their actual origin.

KFG

Obligatory Star Trek Reference

[ebooher]

Where he of course met Guinan and Data and was almost killed by time shifting aliens that were attempting to steal our souls. Wouldn't that be anyones worst season?

Minor nit

[Roadkills-R-Us]

Just great, assuming you have an infinite supply of free ice water. Add teh cost of the ice machine, and it costs a bit more than $24.

Re:Minor nit

[kiatoa]

Exactly, I think the financial folks talk about trading off initial costs for long term running costs. Someone is footing the bill on the electricity for making that ice. BTW the overall energy efficiency of this setup is substantially lower than the equivalent decent window air conditioner (COP of the air conditioner is much higher than the COP of an ice maker due to smaller delta T iirc).

Re:Minor nit

[RevAaron]

nope, from the photos in the FA it looks like he lives off-campus in a rented house.

Re:How about $0 cost of construction...

[shawb]

still gotta pay for the water bill.

Nah... at most rental properties water is included.

Reminds me of me el-cheapo humidifier I once made... put a bucket of water on the ground. Drape a slightly damp towel over the back of a fan down to the bucket and let a process similar to evapotranspiration in trees turn liquid water into humidity. Drops temperature a tiny bit, which is unfortunate as I'd use this in the winter when it's dry indoors. But it is a quick way to dump a couple gallons of water in the

Re:Minor nit

[bhtooefr]

Hmm... Gallon jugs of water in the freezer?

Still uses energy, mind you, but that takes care of the ice water.

Also, I thought that routing the water OUT was a bad idea. Why not catch the water in another bin, or in jugs, and freeze that? Makes SO much more sense...

Re:Minor nit

[gl4ss]

look.. using a freezer(that you run in the same area as you're trying to cool) to cool a room isn't that smart.

I thought the guy had built up some swamp cooler or something like that, as that does really work - but this is just friggin lame/stupid in the long run to use. now... he could refine the idea quite a bit - use ground cooling to keep the water cool for example(just bury some copper pipes or some container a meter into the ground).

"hey i built a cooler. well, i just brought some ice water to my r

One minor issue

[ad0gg]

If he's getting ice from the freezer in his apartment/room, it is negating his attempt to cool his apartment/room. Heat removed from water in the freezer to make the water freeze is put right back into the house by the thermal coils on the back of freezer/refridgerator.

Make ice at night, cool room during day

[billstewart]

If you live somewhere that it gets significantly colder at night than in the daytime, that works.

Or:

[temojen]

Put the bucket outside, in the wind, with a pump to cycle the water through the fan coil in the house, then back to the same bucket outside. Instant swamp cooler with the swamp outside and the cool inside.

It should be quite a bit more efficient than this guy's system.

Re:Minor nit

[anthony_dipierro]

In order for this to work you can't have your room as a closed system.

His room is clearly not a closed system. For instance, there is an input of energy from his power lines.

If it is laws of thermodynamics say no matter what you do it will only get hotter.

That's not exactly what the laws say. Be more specific, and you'll see why you're wrong.

Re:Minor nit

[dreamchaser]

Seriously, especially since for about $120 you can get a low end window unit [thebuzzelectronics.com].

Re:Minor nit

[dreamchaser]

Wow, I should have looked harder. Here is one that would cool a small dorm or apartment and it's only $76 [aafeders.com].

Re:Minor nit

[Skye16]

Things can go horribly awry when putting AC units in... [ctrlaltdel-online.com]

Re:Minor nit

[LurkerXXX]

Why you can get the ice out of the freezer/refrigerator in your kitchen. It just costs a little electricity to make. It makes it by using a condensing coil to use a gas medium to pump heat from the freezer are to coils on the back of the fridge which... then heats the room you are trying to cool. DOH!

Re:Minor nit

[tomhudson]

It's not a minor nit-pick. Its a major flaw. His setup is so much more inefficient than even a cheap ($100) AC.

If he wants to be cheap, why not just take an old fridge ($20), remove the doors, and use the fridge to block the door to his room? Leave the coils facing out into the hallway, and his room becomes cooler - plus the light will always be on, so he can see wtf he's doing.

Re:Minor nit

[Breakfast Pants]

The amount of heat that this increased load will generate is exactly the amount that the ice will be capable of cooling off. Actually that 'exactly' is wrong, it is even more than the ice will be capable of cooling because of mechanical inefficiencies in the freezer itself.

Re:Minor nit

[LurkerXXX]

Yeah, that +5 must burn your ass. Tsk tsk.

The work has been shown multiple times in the various threads, but since you seem to be slow to catch on...

Starting state:

1) Room: temperature x (warm)
2) Water: temperature y (also ~room temp)

Net heat: x + y

Step 1:

Water gets put in fridge. Heat is pumped from water to room.

Result from Step 1:

Call the change of heat in the water z.

(Water gets colder. Room gets hotter. Even heat levels from that part.)

Inefficiency in the fridge adds net heat to room.

The inefficiency heat is i.

Net heat = (x + z) + (y - z) + i = x + z + i

Net Result: increased temperature from inefficiency.

Step 2:

Cold water from fridge is used to run through piping/fan to cool room. It's not done by swamp or other methods. The only thing going on is the warm air is blown past the tube of cool water, bringing the temperature of the room down, and the temperature of the water up. (The water doesn't go through any phase changes through the tubing or anything; it's simply equalizing the temperature)

Result from Step 2:

Heat n is transferred from the air to the water.

Room is warm and so is the water once again around room temp (going out the window now).

Heat m is added from the inefficiency of the fan.

(x + z - n) + (y - z + n ) + i + m

Net Result: (original heat)+ (excess heat)

x + y + i + m

We started with x + y. Now we have x + y + i + m.
Seeing the problem yet?

The water going through the tubing is *not* superheated. It's not warmer than the room air. At the very best it's the same temp as the room. That's if he gets complete transfer. No net heat is removed. It's added.

Water y gets dumped out the window. What are you left with? x ++

Please show your math for your strange theory that makes this perpetual motion machine work, and show how the water in the tube is well above room temperature in order to decrease the net temperature of the room.

And thanks for playing.

Re:Minor nit

[v1]

If he's into thermodynamics he should realize the reason this is appearing to be a cheap way to AC is he's ignoring the need for the supply of cold water. (ice) Wouldn't he cut out the middleman here (and thus, theoretically increase efficiency of the system) by simply leaving his freezer door open with a fan in front of it?

I suppose it might still work running on cold tap-water, but then that could make for an expensive water bill. Although not nearly as much as running your freezer with its compressor

Re:Minor nit

[Cutie Pi]

Actually there's another interesting thing about thermodynamics...

Many people think that if you leave the refrigerator open, it will cool down the house. However, all a refrigerator does is take heat from its inside and move it to the outside. That's why those coils in the back are warm. Thus, if you open up the fridge to cool the house down, all you'll do is make the place warmer (since the efficiency isn't 100%). Also, you'll probably burn out the motor in your refrigerator.

I'll grant that in your parti

Re:Minor nit

[emarkp]

Um, that's the point. His setup is thermodynamically equivalent to opening up the fridge. Thus, he's not actually reducing the heat in the room, he's just moving it around.

Re:Minor nit

[poopdeville]

Since he claims that his contraption cools his room, some step in your analysis must fail. Can you please show me evidence that he kept the refridgerator in his room? Because it looks to me like he was living in a house. And most houses keep their refridgerators in the kitchen.

Re:Minor nit

[racermd]

I hit this through the mirrordot link from above...

This is exactly how a good thermal heat-pump operates. However, a few "upgrades" would make this perfectly viable for a home of 1500+ sq. feet.

1: Make it a closed-loop system, or even a dual-loop system.
2: Use a good radiator and heat-block. Think of a water-cooling rig on a PC, but in reverse and a much larger scale.
3: Use the earth, itself, as both the source and destination of heat.

Most people that have done this for their homes use the earth as a natural heat sink. If it's new construction, they typically dig shallow, but wide. In a retro-fit, they'll drill deep and narrow. Either way, the earth holds a pretty steady temperature below 6-8 feet or so. All that's needed is a way to put heat into it when you want to cool off and a way to get heat out of it when you want to warm up.

This way, all that you spend money on is the electricity to pump the heat-carrying fluid/gas/whatever into and out of the tubes in the ground. If that isn't enough, a small furnace and/or A/C unit can supplement, if need be. Either way, the energy consumed from the utility companies is a fraction of "normal".

I have plans to build a new home in the next 3-5 years, and I'm looking at all sorts of alternatives to just about everything that consumes energy in a home.

1: Geothermal heat pump(s) for climate-control.
2: On-Demand, CNG water heater (i.e.: no tank to keep warm)
3: Solar-powered radiant heat (suplements forced-air from #1)
4: On-Demand lighting (sensors that detect room occupancy)

I'm missing a number of other things I could do, but the goal is to have a home with all sorts of modern conveniences while trying to reduce the energy usage associated with most of them. It's tempting to add a water-cooling loop to the climate-control system for the comptuers. They're already producing heat, so why not just send it directly to it's destination and avoid that pesky conversion to heated air?

Getting back on-topic, this guy hasn't done anything new. In fact, it's rather wasteful to just use a coil of copper tubing tied to the back of a fan. The fact that he's using ice water (as mentioned in other posts) does nothing to save energy costs. After all, he's got to power a freezer to make the ice to begin with, which offsets most of the savings. Never mind that the heat from the water (plus the heat from the machine, itself) went into the living space that he's trying to cool.

And that he's a student, and *probably* not paying for much, if any, of his utility costs. But I digress...

Re:Minor nit

[evilviper]

2: On-Demand, CNG water heater (i.e.: no tank to keep warm)

Unless they've improved drastically in the past few years, these systems are terrible, and they only sell because they trick the "green" crowd into believing they're wonderful, and because of cheapo construction companies who buy this cheap junk instead of a more expensive tank-based water heater.

Basically, when you turn on the hot water, you can expect the first gallon to be scalding hot, and the rest will be barely warmed above room tempuratur

Re:Minor nit

[Fortunato_NC]

Just barely off-topic, but there are apartment units in New York that don't have windows in the bedrooms, however if I remember correctly, residents technically aren't allowed to be called these rooms "bedrooms". These apartments are usually in converted office buildings where what was large, open, "bullpen" areas are walled into relatively narrow apartments with windows along only one end. The areas with windows are used for living rooms, while the non-bedroom "bedrooms" are closer to the center of the bui

DOA

[AmigaAvenger]

I'm a student, with limited funds and a cheap house without air conditioning. To avoid dying this summer, I've built a primitive air conditioner. It's a basic heat pump, using water as the medium. You'll probably need to fiddle a bit with the dimensions of the supplies based on your resources and preferences.

Materials:

Salvage from around the house a:

* large fan
* garbage can

Grab from Home Depot:

* 25 feet of 1/8 inch outer diameter (OD) copper tubing (~ $14)
* 20 feet of 1/8 inch inner

Thinkcycle

[bigattichouse]

You may want to post this on thinkcycle.org as additional information for some of their cooling projects

Siphoning

[sxltrex]

It certainly does suck!

sorry...

Pretty Cool

[QMO]

Too bad it's not child compatible.
(Unless my downstairs neighbors were hoping for rain in their kitchen.

MirrorDot

[eric434]

Next up, a $24 watercooling rig for his web server.

http://www.mirrordot.org/stories/5cb66a4a72a5269bc 29e9dd8f982b3da/index.html [mirrordot.org]

Congrats on making your PH.d. pay for itself!

[jeffmeden]

But sadly this isnt that revolutionary, nor is it very 'green'. It takes a cold source of water to work, and if you have none in your area (tap water wont cut it unless you happen to get fed from a pipe running through a glacier) you have to get cold media from your local refridgerator/freezer. Why not instead rig a direct cycle through your cooling appliance of choice to offer a small, localized cooling effect? It also wouldn't waste water. Just remember, don't try to cool the room with the freezer in it.

Re:Congrats on making your PH.d. pay for itself!

[Spy der Mann]

Well, you could put the heated water on the boiler - there! You save your self the heating, too! :)

Re:Congrats on making your PH.d. pay for itself!

[Overzeetop]

Depends. Around me (and it's nearly 90 outside today) the groundwater temperature is about 59 degrees (both in F, of course). Even the taps come out low 60s year round, once the slug of heated water in the house is gone.

Not green, as the water is just getting wasted, but it may be cheaper for the water than the electricity + air conditioning. Especially if you're not paying for the water bill ;-)

Re:Congrats on making your PH.d. pay for itself!

[MoralHazard]

It takes a cold source of water to work, and if you have none in your area (tap water wont cut it unless you happen to get fed from a pipe running through a glacier)

It's currently 7:51pm in New York City, and the temperature outside is about 85F. The high today was 94 in Brooklyn (my hood).

The tap water temp, though, is still a blissful 61F (after letting it run for about 15 seconds). That's practically icewater, compared to the outside temp.

Since very few residential customers in the city get bille

Canada

[Geekboy(Wizard)]

Dude, you're in Canada. Open the window.

Now you just have to figure out how to keep the snow off of the carpet.

Re:Canada

[RobinH]

Dude, I'm in Canada... was 92 fahrenheit here on the weekend. Plus humidex.

Re:Canada

[Anonymous Luddite]

>> 92 fahrenheit here on the weekend.

weekend? Ontario's been a rotten b*stard for the last week - 30 Celsius + humidity every day.

I'm sitting between two fans, beer in hand, AC cranked. My effing hydro bill is going to make me cry...

Re:Canada

[pipingguy]

We were driving through Brossard Sunday looking for Pont Victoria (most people in the Montreal area end up looking for this stealth bridge at one time or another) and passed one of those digital readout advertising signs that was flashing time and temp. It said -11 degrees C.

Re:Canada

[flithm]

I'm quite upset with you. No self respecting Canadian, or any member of any country other than the lagging-behind-the-times-USA uses non-metric measurements. Canada and fahrenheit should never be mentioned in the same sentence, unless it's one of the following:

"That Fahrenheight 911 show was pretty good eh?"

"Fahrenheight? It's too damn hot in here for your jibberish. Go fill up the $24 AC with ice so we can get the temperature to a respectable level of Centrigadey goodness."

Re:Canada

[Quasar1999]

It's currently 28 degrees outside... check for yourself (http://weather.uwaterloo.ca/ [uwaterloo.ca]), if you can make snow at that temperature, I'd be impressed.

Re:Canada

[caferace]

We make snow at 28 degrees all the time.

Where did you say you were from again?

Re:Canada

[KillerBob]

I'd do that, but it'd make running the air conditionner even more expensive.... It hit 35'C with 70% humidity today, making it feel like 42'C (107'F).

Can't wait until August, when it really gets hot. :)

Environmentally friendly?

[whoever57]

It's cheap, environmentally friendly (just fire the waste water off to your garden)

So, if it is environmentally friendly, just where did the "ice water" come from?

Unless you have a solar or wind-powered refrigerator, I suspect that the overall system is not actually all that environmentally friendly. What is the energy efficiency of the system?

Re:Environmentally friendly?

[LurkerXXX]

So, if it is environmentally friendly, just where did the "ice water" come from?

Ice Pixies magic it up, so he doesn't have to run a refridgerator/freezer to make the ice. Because, you know, those actually produce heat inside the house, which he is trying to get rid of... Pixies. Yeah, that's it.

Re:Environmentally friendly?

[LurkerXXX]

Ottawa? Don't the OpenBSD folks hang out there occasionally? You might not have any penguins, but maybe there are some blowfish. :)

Re:Environmentally friendly?

[kevlar]

I'd say it's more environmentally friendly than a freon-based system, or other gas-based coolers. True, it still requires electricity for cooling the water and running the fan, but there's no real "waste" material from the whole device.

Uhh yeah, except for the fact that he's using his freon-based refrigerator to make the ice, which then ventilates its heat exaust into the same room that he is attempting to cool off using his jerry rigged system.

Beer

[supe]

I think that his garbage can full of ice water should at least have a few cold beers. I mean really, he's in college!

Congratulations

[overshoot]

At first I thought you'd reinvented the swamp cooler [arizona.edu]. On RTFL, however, I find that you've actually reinvented the 18th-century icehouse cooler, which is notably less efficient (like, where does the heat from the icemaker go?)

It didn't seem all that likely that most /.ers would care about evaporative cooling, since even in Arizona they only work part of the year (like now, although today the Phoenix dew point got up to 10C. I woke up just knowing it had gone up because the cooler was blowing full speed and it still wasn't all that cool.) Never mind next month when the monsoons start. AC time then for sure.

Swamp Coolers...

[GI Jones]

I had never heard of a swamp (evaporative) cooler until I moved to AZ. At first, I didn't like the idea of adding a ton of humidity to the air in order to cool some space, but when I bought my first house, I learned that I LOVE swamp coolers.

Newer homes never have them, but the older house that I bought (built in 1979) had a monster one installed on it. During the early parts of summer (when the humidity is low) I can keep my house at 72 degrees when the outside temp is about 100 and my electricity bill is $65/mo.

If I ran my AC unit and kept the house equally as cool with it, I would be looking at no less then a $150 in early summer and $200+ as the temp gets into the range of 110+.

At this point, what I would love is a thermostat that runs both my swamp cooler and AC unit and can determine when to use one versus the other and switch automatically between them. Anybody know of such a device?

cheers.

Re:Swamp Coolers...

[Tsu Dho Nimh]

what I would love is a thermostat that runs both my swamp cooler and AC unit and can determine when to use one versus the other and switch automatically between them. Anybody know of such a device? Nope, and you won't find one. It's a fast way to kill your AC.

I had a tenant who manually switched between AC and evap every day, when we were in one of those "not quite dry enough for evap" months. Her theory was that in the PM, when the RH was low, she could use the evap, then use the AC the rest of the time. Then she called me because the AC was not working.

The first day or so of an AC switchover from evap is when the AC has to remove all that moisture left by the evap. The tenant had been switching often enough that the humidity removed made a sheet of ice on the coils and the AC died. Because it wasn't cooling rapidly enough, she cranked the T-stat down as low as possible, which made the icing worse. Fortunately, there was no permanent damage ot the AC, but she had to swelter with no cooling until the ice caking the coils melted. She wasn't willing to pay the AC guy his hourly to stand there with a blow dryer and melt yhe ice.

Re:OT: Suggestions on swamp cooler?

[overshoot]

I'm using a MasterCool [adobeair.com] that's almost 10 years old and aside from having to change the pads every four years it's great.

Around here you can get them from Home Depot and the installation kit runs about $650; labor is up to you but if you're replacing an old one it shouldn't be too tough to do yourself.

Indoor humidity level?

[rhakka]

evaporative cooling is great, as long as you aren't jacking up your indoor humidity levels which can cause all kinds of nastiness like mold that can kill you or get your building condemned.

If you do this in a non-arid climate, you're asking for trouble, IMHO.

Environmentally friendly?

[iamdrscience]

I'm not sure whether this would be more energy efficient or not, but I would bet not. I mean, really it's using electricity like an air conditioner would -- it takes electricity to make the ice in your freezer (or make the ice you buy from the store).

However, he did say it worked alright with cold water as well and water is included with rent in my apartment whereas electricity isn't. I think I might have to try this.

thermodynamics?

[csimicah]

Wait... this retard thinks that using his fridge, inside his house, to produce ice... then cooling with the ice... is going to make his house cooler? He could accomplish the exact same thing by just opening his freezer door, right? I hope this kid's Thermo professor sees this and kicks him out of school.

hmmmm....

[MarcoAtWork]

#1 you can buy a bag of ice at the gas station/convenience store, not free but then neither is the electricity to run your freezer.

#2 even if you used the house freezer, you shut the door and basically you're pumping heat away from the bedroom into the kitchen, obviously you won't get huge temperature differentials, but 5-6C feels very noticeable when you're trying to fall asleep and it's too hot to do so.

costs

[SuperBanana]

#1 you can buy a bag of ice at the gas station/convenience store, not free but then neither is the electricity to run your freezer.

The store needs to make a profit on top of the cost of the electricity to maintain the machine, and the ice...

...supplied by the ice company which bought the machine, maintains it, and freezes the ice, and trucks it to the store from their "plant"...and make a profit.

You do realize that 1kW/hr costs about 22 cents, whereas a 20lb bag of ice costs about $5, right?

You have to move 330J of energy to freeze one gram of water, basically. We'll assume a 50% efficiency here (pretty poor, I believe). A bag of ice, say, 20lb- would need about 3 million joules (watt-seconds), or 6 million watt-seconds of electricity. That's 1662 Watt-hours, roughly.

Or about 36 cents.

#2 even if you used the house freezer, you shut the door and basically you're pumping heat away from the bedroom into the kitchen, obviously you won't get huge temperature differentials

Most refrigerators are virtually incapable of pumping that much heat (there's a reason they're insulated), and furthermore, are designed to work at a temperature range 60-90 degrees cooler than what you're asking of it. Ever noticed that a fridge takes forever to get from room temperature down to operating temperature?

This idea is so stupid, I can't believe I just wasted 5 minutes on this post. I want that 5 minutes of my life back.

Re:thermodynamics?

[PondScum]

The goal was cooling a room.

While I agree that there are far more elegant ways to do this, You can still cool a room this way and not disobey the laws of Thermodynamics.

The heat generated by the Fridge stays in the Kitchen. Close the door and now you have effectively transfered heat from the cool room (bedroom or livingroom) to the kitchen. It is now far easier to relax.

Think it through before calling someone a moron.

Re:thermodynamics?

[csimicah]

Huh... does U-Waterloo water also come with ice chunks and frozen bottles of water in it, as pictured on the site? That must be hell on the pipes!

Neat, but probably not very effecient.

[Zerbey]

I don't think this would be very helpful in Florida, but you never know. I wonder if the inventor has tried it in 100% humidity/100F+ weather? :-) The major sticking point is needing the ice water to begin with of course.

Being without A/C for a week after the hurricanes last year was no fun at all! I'm just glad our generator had enough juice to power a window air conditioner (but the gasoline cost a fortune :().

Building a home brew A/C that was energy effecient would be a very useful project this year,

Bah! Put that reservior in the fridge and recirc!

[wernst]

Not a terrible bit of redneck engineering (and I mean that is a positive way), but I can't imagine anyone having a limitless supply of ice and water.

Not that the idea I'm about to present is any better, but this guy really needs to make this a closed system. Put that bucket'o'water in the refridgerator (or freezer), get an aquarium pump, and run the pickup line to the bottom of the bucket and the return line on the top of the bucket. Cut out the door gaskets to allow the lines to go through, and just add s

Most enviro friendly method to not overheat

[WillAffleckUW]

is just to replace the standard incandescent lightbulbs in your house with compact flourescent bulbs.

this will result in you using about 1/8 the electricity to get the same light, but drop the heat output from lighting - a major contributor to household heat - to virtually nil.

I used to have a problem in my new house with having to get a fan until I realized it was mostly heat from lights that was making it hotter than a normal open window breeze could cool. Then I replaced my incandescent bulbs (well, most of them) with flourescent bulbs and suddenly it was cool enough I didn't even need a fan at all.

Now, if the external temperature is above about 98 degrees Fahrenheit (30 C, I think), you may still need to do the water evaporator you describe, but the energy used by it will still be lowered by switching to compact flourescent bulbs for lighting.

Oh, and get a flat panel LCD monitor - that will save a lot of energy usage and heat output as well.

Save the fan to cool off your computer, not your room.

addressing all the flames/legitimate concerns...

[inkey string]

number one, yes i realise that in a closed system freezing ice to cool yourself off is foolish. this is why i make ice in the kitchen, and cool my room off at night.

which addresses the why no recirculation/you need an infinite supply of ice criticisms. this was designed to cool me off before bed, so i could fall asleep without wanting to kill myself. once the bucket runs out of water/ice, it just becomes a regular fan which is fine once the house cools off in the wee hours. plus i dont have to worry about knocking anything over in a morning daze.

ive rigged it up to a slowly flowing garden hose which will keep things cool indefinitely, but i find it easier and a bit cooler to just pick up a big bag of ice and dump it in when it gets really hot.

anyways, take it or leave it. and to the graduating chemmie that said he was ashamed to call me a student - come visit me at my office by the weef lab (e2-1311), im sure i can address any of your concerns to my satisfaction.

CostCo $50 for 5000 BTU

[jbridges]

Spend another $26, and buy a real airconditioner for $50 at CostCo.

It's $99.99 with an instant $50 off rebate at the register.

Less work too.....

Re:CostCo $50 for 5000 BTU

[One Childish N00b]

Spend another $26, and buy a real airconditioner for $50 at CostCo. It's $99.99 with an instant $50 off rebate at the register. Less work too.....

Yeah, and if Linus Torvalds had dropped some cash for UNIX, he wouldn't have had to write his own. Less work there, too.

I have to ask if you've ever built anything yourself, because there's a real pride to be enjoyed in knowing that what's working for you was built by you that seems to have passed you by - I'm writing this message on a computer I built mys

Bend the copper using sand

[ishmalius]

I don't know if this guy ever took shop class, but the simple old trick of filling the part of the copper tubing to be bent with sand will help prevent it from collapsing from a too-tight bend.

While the freezer probably isn't the best way...

[foxtrot]

...to cool a room, as has been noted repeatedly, a few refinements that can be done easily and cheaply:

1) Get a second trash can. Drain to trash can number 2. This will allow you to save water, plus:

2) Put salt in the water. The ice and chilled water mixture gets colder with salt.

You probably don't want to drain salt water to the yard. :)

You can run from one trash can to the other, then when it's done draining, swap one can for the other and ice down the other can. If you've got some freezer space to dedicate to the project, the bottles of ice are probably an excellent idea-- have a set in the freezer and one in the heat pump.

Re:While the freezer probably isn't the best way..

[k98sven]

>>Put salt in the water. The ice and chilled water mixture gets colder with salt.

>Errggh.... no it doesn't :}

Errgh.. yes it does.

Salt in the water just allows it to be a liquid at a lower temp.

Which means what? It means that you've shifted the equillibrium between ice and water to a lower temperature. Which will lead to the ice melting faster until the depressed freezing-point is reached. (after which the melting will actually proceed slower than before since the whole solution is colder)

Homebrew swampcooler

[gessel]

Years ago, during a heatwave in Oakland, I built a homebrew swamp cooler with some muffin fans and a mist nozzle from McMaster (like 32215K11).

From thermodynamics, the say you have 1kg of water to work with:

Changing it from ice to water: 334kJ
Raising it from 0C to 25C: 104kJ
Converting from liquid to vapor: 2,260kJ

Compared with vaporizing water, melting ice is trivial.

For swamp coolers to work, the humidity has to be low--if it's high the ice bucket trick is a good one. But for those in dry hot climates, a swamp cooler works well.

I connected mine to a hose spigot with 1/8" tubing, which supplied a continuous flow of water to the mist nozzle, which was mixed with a good flow of hot dry air from the fans, and resulted in a good flow of cool slightly damp air.

Capacity

[ColaMan]

This is all very well and good, but he's missing one thing - capacity.

Air-conditioning systems are sometimes rated in "tons". That's "how many tons of ice required to melt in a 24hr period to get the same cooling effect."

Surprisingly, in AC terms, a ton is not a very large unit. A typical car air-conditioner is about 2-2.5 tons. This size AC is capable of cooling about half a house. So, a 5kg bag of ice? Forget it. Go buy a real air-conditioner. Scrounge around - 30 bucks can buy a decent old second-hand unit.

Coral Cache

[Spy der Mann]

http://www.eng.uwaterloo.ca.nyud.net:8090/~gmilbur n/ac/ [nyud.net]

Will someone edit the submission to replace the URL, please? Sheesh.

No, it isn't

[Roadkills-R-Us]

A swamp cooler pulls the air through the actual water. It uses evaporation for the cooling effect. That's rather different than this, which is just a crude radiator. effect.

Re:To be pedantic...

[amliebsch]

Actually, it's not even that, since the cooling simply comes from the fact that the water is colder than the air to begin with. It's just "blowing air across a cool surface". But with a siphon, to make it all science-y and energy efficient.

Re:To be pedantic...

[Quikah]

Swamp Coolers work by passing air through a moist pad. The water in the pad is evaporated cooling the air. This works by passing air through a cooled coiled tube, no evaporation occurs during the cooling process.

Re:To be pedantic...

[Overzeetop]

Well I didn't RTFA, but based on the text someone posted here (just above you) this is not a swamp cooler. Those work by an evaprative process where the temperature of the air drops as it passes over a wet wick. The evaporation removes energy from the air, reducing the temperature. Unfortunately, they also add moisture to the air, so you get a cooler, more humid environment. They also don't work when the humidity is high (saturation=no evaporation). They're good for desert climates, but not good anywhere el

Re:At first, it looked like a great story...

[MrAnnoyanceToYou]

That's exactly what I was thinking. For an extra 20$, I'm sure you could get a bike-pump powered valve that would run the water through the tubing, a lid for the garbage can, and some duct tape to seal the garbage can in the basement so nothing got into it.... Enough extra tubing, and you're going to have a closed loop.... That way you don't even need to fill the garbage can with ice water regularly... You do have to pump up the thing every once in a while, but you never have to suck on the tube....

T

Re:At first, it looked like a great story...

[temojen]

This design should work just as well with filtered brackish water.

Good show, but not a great idea...

[benjamindees]

Other than the obvious ingenuity involved in the creation of this device, the reason things like this don't exist in the real world is that they're hardly efficient. And comparing the purchase price instead of the operating costs of such a device is a sure sign you're missing something.

Air conditioners are unbelievably cheap and unbelievably efficient nowadays.

As others have said, this setup has all sorts of problems, from a reliance upon a source of ice that may very well be dumping more heat into the local environment than it saves, to wasting water.

Though this system doesn't use a pump, a recirculating system with a small electric pump could end up creating more heat than it saves.

If you're really bent upon saving energy in a cost-effective fashion, adding insulation is almost always efficient. Good blinds on the windows are also a great investment.

Re:Good show, but not a great idea...

[Technician]

As others have said, this setup has all sorts of problems, from a reliance upon a source of ice that may very well be dumping more heat into the local environment than it saves, to wasting water.


Very good point. Just where is the fridge located that produces the ice? Where is it putting the heat. The fridge is not included in the price of the project. Why not just take the door off the fridge and mount the fridge in the wall to expell the heat elswhere?

For those who don't know, fridges use a small c

mirrordot

[kryogen1x]

Thank you mirrordot. [mirrordot.org]

Re:Fan?

[Quikah]

Yes, but it would take a lot longer to occur. For example he could just point his fan at the bucket of cold water, however you have a limited surface area for the air to pass over. Running the water through the coiled tube increases the surface area, lowering the temperature much quicker.

Probably some other factors as well, I had a bit of a dumb thermodynamics teacher (not to mention it was over 10 years ago and haven't used it since!).

Re:The ol' hose on the roof trick

[gerardrj]

Your roof is only one part of the issue, probably a minor one if your have an attic.

During the daytime the sun warms the roof and walls of a house. The surfaces most perpendicular to the Suns rays will get hotter, faster.

In the morning the sun is low in the sky and the light rays are mostly perpendicular to the house walls. Since the air is still relatively cool from the night period, the heat imparted to the walls is mostly released back to the atmosphere.

For the mid-day the walls are washed in light mo