Homemade air conditioner

Step 2 Attaching the tubing to the pump

Now, the cheapie pump I bought would only fit 1/2" ID tubing, and they didn't have anything that would downsize it to 1/4" for me, so I just rigged it up. As you can see in the first and second photos, 1/4" tubing fits quite nicely around the copper tubing. In the third photo, you can see how I just inserted the 1/4" into 3/8", into 1/2" tubing, which would then fit onto the pump. This of course leaked, which necessitated the use of hose clamps, photo 4. I feel that this greatly reduces the effeciency of my pump, but now I have a reason to buy a bigger, stronger, more manly pump! Either that, or buy bigger copper tubing, which is not as exciting.

Comments

[jpnagle59]

poo-poo on u none-believers, and number crunchers...A for effort...A for the thought...A- for not getting the little spring benders at the hardware store to bend the copper tubing without kinks. I would reconnoiter the near by your areas for more copper tubing, bend it tighter to make more surface area for the air to flow over, to cool better. Also, it you have a freezer, get some of the 'gel' pack re-freezable do-hickey's, put them in the boss's freezer, and let him pay for the ice....living here in Texas- which the last 28 days has been over 105f , I would do this in a heart beat....Danka....

[xtr3mx7]

You'll certainly benefit from it rather than using an AC which uses around 1,000W/h for a 10,000BTU unit.

The problem I see is with the pump, it should be powerful enough to send the water across the copper tube. Recommend one with at least 1,500LPH. As I have a small water pump same as per picture above and it only provides 230LPH.

Are you sure a small water pump would be enough for the water to flow?

[seb1188]

 That makes no sense, one watt (W) is one joule (J) per second. 1000W/h (=1KJ per second per hour???) is a measure of rate of change (acceleration) of use, not of the actual energy use.

You're suggesting that freezing water using similar if not identical technology (so same efficiency) and then using electricity to pump it around as well is going to be more efficient than an air conditioner, which doesn't have the additional pump? When an air conditioner, might I add, doesn't just throw the waste warm air back into the room anyway but blows it outside, unlike a freezer, which won't actually remove any heat from the building at all?

A/C is more efficient. Just a big initial investment.

[joosh]

I think he meant kilowatt hour, which is the amount of watts an appliance using in an hour. He is just saying his AC uses 1000 watts per hour or 1 kilowatt hour of energy. Its just another way to measure the amount of energy something uses.

[dbixler]

The problem with this project, and projects of its kind, are the laws of thermodynamics. Granted, if you're doing this to use during camping or something like that where AC is unavailable, it has its merits. However, unless your cooling mechanism is free (which, for the author, it is) you're actually spending more money. I'd bet my life's savings that this is far more inefficient than a window mounted AC unit. Because of that, it probably takes more energy creating the cooling compound (ice, in this case) than what you're going to save cooling a room with something like this.

[ewhipped]

Not fully understanding the laws of thermodynamics why would more money be spent this way? If you fill 2 liter bottles full of water you are going to spend a nickel tops on water that you can use multiple times. And unless you are plugging in a freezer for the sole purpose of making ice for this contraption I don't see how you can use more energy. From everything I have heard it is easier on a freezers compressor to have it as full as possible. My freezer only has 4 ice cube trays and some liquor bottles. Plenty of excess space to be utilized there.

[hotbboj]

 The compressor would have to run more, because there would be more heat absorbed into the evaporator inside the freezer. 

[dbixler]

Suffice to say, you can't fool Thermodynamics. The amount of energy spent making the ice is "ALWAYS" going to be more than what this type of cooler will ever give back. What does your freezer produce when it makes ice? Heat. Where does that heat go? Into some area in your home that's going to be cooled. The cooling process will use more energy, thus the inefficiency.

Now, in your example, you say your freezer has plenty of space. If that's the case, then it should only run to keep that amount of "solids" cool. When you use the ice cubes, for example, in the cooler from this article, and then fill the ice cube trays, your freezer will then run to make new ice. This in turn generates more heat (and the amount of heat generated will be greater than the amount of cool that the ice cubes generate). Think about it this way, if this kind of thing were truly feasible, why not just leave your freezer unstocked and opened to cool your house? Because it's not 100% efficient. The inefficiency is reflected as heat (not to mention the electricity).

I realize I'm not very good at explaining Thermodyamics, suffice to say that your freezer is far more efficient than this fan and a copper tube. I'd even go so far as to say if you REALLY wanted to run something like this, then buy a freezer, drill holes in it and run the copper tube through the freezer into your fan. At least then it's being cooled by something more than ice cubes (and you're not potentially wasting the water to produce the ice).

I'll refer you to this article and maybe it'll make more sense :).

http://en.wikipedia.org/wiki/First_law_of_thermodynamics

[lksmith]

In my case, I have a Huge ice machine at work where I can get all the free ice I want. and since I work most days I just chunk a couple of ice chests in, and if I use a 12v fan with twin deep cycle batteries that are wired to a charge outlet on my truck. With my version of this baby I spend no extra energy to run it and it keeps my shop cool and I only occasionally have to turn the AC in my shop on

[hotbboj]

By using a solar panel and an inverter to run 12V, you could save even more

[dbixler]

Correct. If everything except the electricity used by the fan is free, then this will likely save you money on cooling.

[lksmith]

even better is that the electricity to run the fan is also free, since it is run off a battery. The energy to charge the battery (ies) comes from either a solar panel or from the alternator on my truck during me daily commute to/from work

[hotbboj]

 I remove my last comment.

[dbixler]

Ha! You use the word free very liberally :). Granted, if it comes from a solar panel then yes, it is mostly free. But again, if it comes from an alternator, it is most certainly not free. You have to consider the fact that alternators are subject to the same loss due to inefficiency as the previous system. Plus, batteries are one of the most expensive means of driving a system, next to wood, maybe. Any time you are taking one form of energy and converting it into another, there is ALWAYS a net loss. Even in a "perfect world" you'd still be spending money on gas to drive the engine to drive the alternator to charge the batteries. But we do not live in a perfect world. ALL of the components in that system are subject to loss and inefficiencies.

[lksmith]

the reason I say charging off the aletnator is free is because unless I am on interstate going 70+ ( I get 16mpg then) my truck gets 15mpg whether i am pulling a trailer load of hay or no extra weight at all. I am going to drive to work 5 days a week. It doesn't cost me any extra to hook the batteries to the truck to charge whilst driving to/from work. I am not saying that it is a lossless system I am saying that it doesn't cost me any more than if i wasn't charging them. Wood for me would be the cheapest way to power my system since there are literally hundreds of forests all around me and thousands of dead trees. That is how my family has always heated their homes and shops during the winter

[South Texas Connection]

You know some people get so technical on things the main idea gets lost in the confusion. There not going to do it, don;t want to do it, just tell you how to do it & confuse the issue so in the end, what is being discussed has nothing to do with what the project is all about in the first place. JMHO STC

[iBurn]

It actually does. Your engine has to work harder to charge the batteries, however minor that change may be, it's there, and it's probably more energy efficient to charge off an AC outlet.

[elnino2783]

You're missing the point. His freezer is always on, thus it will be cooling things regardless of if he is making more ice. You could assume that he is wasting all that cooling goodness simply because he is not constantly producing new batches of ice in the extra space of his freezer. Also, if his freezer has static frozen items (steak/chicken/etc. that only come out once a month or something) Then some of his cooling power has been stored in those objects and his freezer has to work less to make the ice. So simply because he doesn't have to fire up the freezer every time he makes a batch of ice, he is saving energy. Basically the freezer is already at a steady state temp (for the most part, only turns on to re-cool, less so if frozen items are in there already) so he is not wasting additional energy, he is making more efficient use of energy that would have been wasted anyways.

[dbixler]

Actually, no, I got his point. Since I'm not a scientist, I cannot explain it further, so I'm sorry. I'll try to explain it differently one more time and hope that someone with a more scientific background than myself can help. Making ice simply to use for this purpose is not energy-efficient nor cost- efficient. The cost to maintain ice is far less than that to make ice, and if you're making ice simply for this purpose you're losing money. It's as simple as that. A freezer will keep ice frozen for a long, long time (unless your freezer sucks). The only loss freezers experience is due to poor insulation. If the ice is free, sure, he'll save money. But in the end, it's a net loss. Loss from the freezer making the ice (the mechanical work done by the compressor). Loss in the fan motor that spins his fan. Loss in the electricity used by the freezer, the fan, the pump, etc. Just speaking of downright cost, buying a decent box window AC unit will provide a far more cost-effective method for cooling a room (not to mention better looking and using less space). Hopefully someone out there more knowledgeable in Thermodynamics can help me out here.

[joosh]

I understand what you are saying completely. Basically to make ice not only do you need to take the heat out of the water to turn it into ice, which then is released into you house, the freezer also generates heat through energy loss in its mechanical and electric parts. If I am continually making ice I'm releasing all that heat into my house making it hotter, and when i then melt that ice to cool my house I'm getting an energy loss costing more money. Sure if a freezer is full of frozen items its using less energy, but if I put water in it to make ice, and when the water is frozen take the ice out and replace it with more water the freezer is working harder while making more heat.

[iBurn]

*raises hand*
I get it.
...Well...I got it to begin with...but I still get it, and you're still right.

[Thenwcp]

I see what you're saying here.....
The home is acting as a closed system, so.. without taking into account the fact people are moving in and out of the home...there is no mass coming in the is no mass coming out. However energy is being passed through due to ambient losses through walls and windows.... ideally heat in=heat out therefore in order to make the ice, heat has to be transferred from the water to..somewhere to make ice, this heat is transferred into the home and diffuses into the air therefore making the home warmer... the ice then can only cool the home back to its original temperature due to the laws of conservation of energy. therefore since heat is still coming into the home from the outside environment more heat is being put into the home than being taken out.... therefore heat in>heat out so.. already in an ideal world this unit is not cost effective....
however this is pretty awesome.

[elnino2783]

Yeah I see what you mean, basically there is no such thing as a lossless system, but I doubt this will cost anymore than an AC and I'll try to say what I said before with a little different wording. Basically, the freezer is going to run regardless of if he is making ice for this system. So it is a sunk cost since he's really using it for other reasons, he just has more capability out of it that he can grab by making some ice on the side. Also, all the places I have lived water has been incredibly cheap and the fees from the company cost more than my water usage. Also, unless I'm wrong, box fans are nowhere near the power suck that AC's are. My lights don't flicker when I turn on a box fan like they might if I turned on my AC. So running an AC will definitely cool your room 20-30 times better, but will also cost you a ton more to run. One other thing to consider, while you may get that much better cooling with an AC, the user may not need that much cooling to feel comfortable in the heat, and they may not even need it year round (I've only lived in Northern US states and could only get 2-3 months of usefulness from AC). So it might be like using a bazooka to kill a mouse, it's just a little overkill.

[joosh]

You are forgetting something here. Yes, he does have his freezer running all the time, but the contents are usually all at the same low temp. That means the freezer doesn't have to work much to keep it cool. Only from opening the door and heat getting in through the insulation. Now let say i keep adding in water to the freezer that is warmer then what is in the freezer. It now has to displace all that heat, and where does all the heat go? Thats right into your house. So as it stand you can even cool your house this way. This is assuming you have a 100% efficient freezer. Knowing that yours is not your freezer generates heats through the friction of mechanical parts and also heat through the use of electricity. Basically if you are trying to cool your house this way you are not doing a every good job because in reality its a heater.

[seb1188]

An AC is better, cheaper and more efficient than this.

When a freezer is running, it isn't permanently "running". It maintains a temperature. If you add a big bottle of room temperature water to your freezer, it has to work harder to cool down that water and freeze it, and harder still to cool down the air you let in when you opened its door. The actual cooling of a freezer has similar efficiencies as an AC. The wasted energy in cooling the air you let into the freezer, and cooling the hot air a freezer releases into your home, makes an AC much more efficient overall.

In the long term an AC will cost less to run than this, assuming you use both to achieve the same temperature changes over the same period of time. And most ACs have thermostats and controls that allow the user to reduce cooling if they don't need that much.

[prometheus9000]

I built one and it works well, but I use frozen water bottles instead of ice. Also, I used soft copper which is much easier to bend. The down fall of building one of this is that the ice does not stay cold for long. However, the instructable was easy to understand and nicely done. Ideas like this one is why I love this site. Good job ehensel1

[improv.cycling]

I'm going to build one and I going to try using a tec unit but i was wondering if any one knew the best way to "get the cold off" the cold side.

[SniperInTheDarkness]

use a heatsink, but the hot side needs to be cooled very efficiently otherwise the cold side just gets warm.

[radiochemist]

yeah a thick aluminum heat sink and a cpu cooling fan from radio shack blowing the hot air away from the fins can help you get rid of the heat. if you have a PID controller, thermocouple and a DC solid state relay you can set the temp of the cold side and conserve your battery power.

[radiochemist]

then coat the surface of the cold side of the TEC with heat sink grease and bend your copper tubing into a tight Z or N type shape so that can cover as much of the cold side of the TECs as possible and add alcohol or antifreeze to your water so it can't potentially freeze and block your tubing and kill your pump. make it solar powered if you can, TECs will draw a lot of energy from your batteries if they're able to and you won't be able to use it for very long. It's probably not going to be any cheaper than an AC air conditioner if you make it that way but this is how you can get around Dbixlers problems with it.

[SniperInTheDarkness]

Wow, That was really helpful as my 2 projects are currently at a stand still because i cant get the hot side to cool efficiently but, i've rigged up an old tec fridge to 2 computer power supplies, one cools efficiently (the stock one) as it has a huge heatsink and a powerful fan on it, the one that i'm trying to add has a slightly smaller heatsink and a fan of about the same power, and it gets way too hot. All of my attempts to cool it have been futile, i've tried all kinds of fans and the biggest heatsink that will fit on it, would it just be better to put a resistor on it so it doesnt get as much of a load, in turn not heating as much because at this point, the "cold" side gets warm at best and the hot side and its heatsink get burning hot, so hot that i am unable to touch it with my bare hand. Or would it be better to devise some large cooling system just to cool that component? Thanks in advance!

[radiochemist]

yeah it will definitely work better if you are able to limit the amount of current that goes into it. Give it a low voltage between 1-5 volts and put a current limiting diode on it rather than a resistor alone. You'll have to experiment to figure out your optimal current. Start with giving it 50% of the rated wattage, if it's not cold enough, increase the current but keep in mind the colder the side is, the hotter it's gonna get when the power turns off. There will be a sweet spot that is cold enough to get the AC working but not so cold that when you turn it off the cold side gets too hot to touch. I'll show you the type of heat sink I used for my TEC projects that I got off ebay. It's way thicker than anything you would find at radio shack or anything used for computer parts.
http://cgi.ebay.com/NEW-HEATSINK-EXTRUSION-10-125-WIDE-ALUMINUM-HEAVY-BIG_W0QQitemZ170364201291QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item27aa7f694b&_trksid=p3286.c0.m14#ht_500wt_1182
He should have different lengths available that are cheaper but that's the kind that works best for TECs. Also you need to have some thermal glue to get the hot side of the TEC to stick to the most surface area of the aluminum. they have to be held on their super tight in order to work the most efficiently since sometimes they can warp slightly. I ran into the same problem when I had I tried to use TECs with solar power. If the current is too high for your heat sink, both sides will get extremely hot. Also it is important to note that when you turn the power off, the cold side will get really hot and the sudden temperature shifts will warp the TEC so sometimes like in aquarium chillers, they have another heat sink on top of whatever you're cooling to dissipate the heat that comes back.

[SniperInTheDarkness]

thanks, that helps a lot. :D