Too hot? Use ice and water to remove heat from your body. A 12 volt pump moves cold water through tubes strapped to the back of a car seat, lawn chair or even indoor furniture. An ice chest of nearly any size can be used.

Within seconds of starting the pump you'll feel like someone dumped a glass of iced tea down your back!

Race car drivers use an expensive version of this with a heat exchanging t-shirt under their jackets to keep cool.

The parts cost less than $100. I've made these for classic cars, electric cars and for lawn chairs. They'll make you more comfortable if you don't have air conditioning and have to be in the heat.

Warning: Do not use for extended periods of time. Should not be used if you have poor blood circulation.

Step 1: Parts and Tools


Ice Chest - any size, larger can hold more ice for longer cooling. 
Plastic beverage bottles: At least two of any size. One to freeze and the other to use in the backcooler. I use two 1 liter pop bottles. Fill with fresh, clean water 2 inches from the top to allow for expansion. Remove the labels! The pump doesn't like label fragments!

10 feet of 1/4" od vinyl tubing: - get the drip irrigation tubing; it's tough, cheap and withstands UV
5 feet of 3/8" od, 5/32 id vinyl tubing: Usually clear, does not have to be food grade or reinforced.
3 inches of 3/4" id vinyl tubing: Clear - Size to fit your bilge pump outlet.
Two 1/4 to 3/8 reducer couplers: I used Eldon James C4-2.5NP
Two 3/8" quick release couplers: Optional
( Colder part number APC22004 and APC17004 from www.US Plastics.com)
Do not use drip irrigation fittings, they will leak when you move the tubing around!
One 12v submersible bilge pump, 350 gallons per minute for single seat, 500 gpm for a double.
One cigarette lighter plug with 2A internal fuse
3 feet of 12v 2a wire - Size to your needs
Two crimp connectors
One square yard of 1/4" nylon mesh or similar fabric, or a car seat cushion.
Two 6' nylon straps and buckles
UV resistant fabric
Heavy thread, UV resistant
3 small nylon cable ties

Drill & bits, 5/32"
Upholstery needle

Step 2: Ice Chest Set Up

Drill two holes for the 3/8" tubes and one for the wires. Size your drill bit so they are snug. The position must be near the top of the chest. The lines will tangle less if it's near the pivot of the handle, it depends on how your ice chest is made. Think twice, drill once

Bilge pump: It will work in any position so I didn't mount it. Most pumps have a mounting bracket, you can try gluing it to the bottom or side of the chest. It's easier to clean the pump and chest if it's not mounted. My pump has a 3/4" OD outlet, find the tube size and adapter to fit yours. The seal does not have to be water tight on the bilge pump.

Connect the wires to the bilge pump wires outside the ice chest. The Rule model pumps are not polarized, but if yours is connect it correctly! If you want to put a switch in line, go for it. You can also wire it to your car's fuse box with a disconnect.

The supply and return tubes are interchangeable. Make the lines long enough to reposition around ice bottles if needed.

Use the nylon ties on the inside to keep the tubes and wires from being pulled out. Not too tight! 

Step 3: Seat Heat Exchanger

This part will take the most time.

The idea is to put about seven feet of tubing on the back of a seat so it contacts your upper back and can absorb heat which cools you off.

Use nylon mesh like that pictured or get a car seat cushion and fasten the tubing to it. I used UV resistant, heavy thread with an upholstery needle. My technique needs some improvement and if anyone has any suggestions on how to attach the tubing to the mesh securely and quickly, let me know. I did try threading the tubing in and out of the mesh, but it distorts the mesh and takes a long time.

The tubing must not be kinked, so any pattern that you like should work. I sized it so my back would cover the tubing and reduce condensation. Place it on your wide upper back, do not use it near your kidneys in the small of your back.

Supply and return lines are interchangeable.

I had a friend sew some UV resistant upholstery fabric into a tube, about 1" diameter to hold the vinyl tubes together, insulate them and reduce condensation. Don't sew? Use pipe insulation, taped on plastic packing material or leave them bare.

The length of the supply lines depend on where you use this. Shorter is better.

If you want two back coolers you'll need to find 3/8" Y adapters.

Step 4: Adapting, Improving & FAQ

I've made about a dozen of these for friends and family and this is the latest and greatest version. The first used drip irrigation connectors and leaked like crazy. I like the mesh because it's not bulky and dries quickly. My next one won't have any straps, it'll be a Swiss cross shaped mesh attached with elastic cord in the back. I have put t-shirts over the mesh and seat but it reduces efficiency.

I'm open to any suggestions and am happy to answer any questions. Let me know how you use yours and if it's helped you beat the heat.

Tips: Put a teaspoon of bleach in the ice chest water to keep it fresh. Do NOT drink the ice chest water, DO drink the melted ice water from the clean pop bottles. You can put ice directly in the ice chest, but you'll have to empty the water later. Swapping melted bottles for frozen bottles is easy, no mess. Any size bottle can be used, remove any paper labels because they'll jam the pump.

Here's some questions I've heard...

How about using it as a heater? A. You'd have to have a thin layer of clothes to use it as a heater, go for it.

How about sitting on it? A. That might work, but you could pinch a hose and reduce flow.

How about a head band or a hat with some tubing? A. Sure, go for it.

How about condensation, won't it get wet like a glass of iced tea? A. Yes, a bit, but it's better than sweat and it will help transmit heat from your skin to the tubing. You want cool AND dry? Get air conditioning.

My back went numb! A. Don't use it for prolonged periods, turn it off for a while or lean forward. When your skin gets too cold the blood flow decreases and it's not as effective pulling heat from you. Do not use this if you are diabetic or have low blood flow.
This seems to be made as a cousin to the Red Neck Air Conditioner. This is a great alternative! Far better concept for personal cooling. Why cool the air, which can take a longer time, if you can cool just yourself? I think this would be perfect for the car that I'm building. I was gonna go without A/C, but this would make summer driving much more comfortable. I've got the helmet cooling system done, but I've GOT to use this as well. I live in Iowa. Our summers have heat and humidity walking hand in hand. I'm SO glad that I ran across this! Great idea and Instructable!
RSM, thanks for the comment. Good luck with your project and let us know if you can improve on this in any way.
could use the coolint used in car i think it is called freeon
This is a low tech way of removing heat from your body. Freon requires a compressor, valves, high pressure rigid tubing, controls, etc. This is simple, easily made and effective for cars, houses, lawn chairs that don't have complicated air conditioning systems. <br>
I made a similar set up only I used 1/4&quot; PEX tubing and connectors for the back heat exchanger, the tubes run vertically with about ten plumbed in parallel, the water keeps the cooling even and the pex doesn't need a webbing to keep its shape. Thanks for this idea!
R,<br> Great idea! I've never worked with PEX, it wasn't around when I started working with tubing. Now it's in every hardware store / home center. <br><br> -Ev
i read that some air dusters contain difluoroethane, maybe it can be used as a refrigerant for a DIY system?<br>or the liquid itself might be used for cooling
Simple is good. Water is cheap, ice is cheap.
hey im a big paintballer and i have an idea for a cooling system to put in my combats. i have an idea of how i want to do it and was just seeing if anybody has an idea for a small contraption to use as a heat "mover" what i mean is i cant leave ice in a container (chubby bottle or something small that fits) and expect it to stay cool all day so when it melts i want to be left with something that works like a refrigerator. any ideas?
This can scale well. You don't need a rigid ice chest, it could be a soft sided cooler in a backpack. Use smaller bottles, frozen 12 oz pop bottles. Keep a bunch in a bigger ice chest and swap out as needed.
&nbsp;yeas auctually i am using pods in my &quot;prototype&quot;... but now another snag is there appear to be no pumps that run on a 9v battery
Carrying an ice cooler with you would work a lot better than trying to run a Peltier heat pump from batteries. A TEC (thermoelectric cooler, a.k.a. Peltier junction) is a seriously powered device that requires energy input equal to its work (as in, to remove 20W worth of heat, it requires 20W worth of electricity). It isn't only unpractical to carry a car battery while trying to paintball, but the Peltiers to the skin are dangerous: each of them can be smaller than a credit card and only create a cooling effect worth 20&ordm;C, yet pump plenty of watts and can be stacked. I know of this guy who made a Godzilla costume and, wanting to ignore the Disney Rule (15 minutes in, 45 minutes to cool down), had 2 stacks of 3 10W TEC modules strapped to his kidneys (a good reasoning, as (A) the human body produces 60W worth of heat when idle and (B) 20% of a bloodflow goes through the kidneys), and hosing rerouting the heated air from the heatsink fans to the mouth. And he had friends running around, keeping his extension cord connected. He did violate the Disney rule: he ran around the convention's halls for a half hour before he stopped for a cold drink. He apparently passed out as soon as he sat, and later he was treated for general hypothermia and for frostbite to two credit-card sized spots on his back. Last I heard, he modified the costume so the TEC modules pump chilled air from his tail. He still cheats the Disney rule, though.
use a peltier module. stacking them amplifies the effect. use it as a heat exchanger in conjunction with a heat sink.
My friend and I built something like this in a backpack form.<br/><a rel="nofollow" href="http://www.motormayhem.net/2008/09/07/climate-controlling-backpack/trackback/">http://www.motormayhem.net/2008/09/07/climate-controlling-backpack/trackback/</a><br/>
Had a question about the quick release connectors. I used Colder part number APC22004 and APC17004 from www.US Plastics.com.
Where did you get teh connectors?
Mfg for the reduction fittings is Eldon James. You can buy direct or from www.valueplastics.com or www.usplastics.com. Look for Tubing & Fittings. Someone suggested using CPU cooling fittings, not sure of suppliers. Do not use drip tubing fittings, they leak!
As a boater, I know that ALL bilge pumps are made to be submersible. If they weren't submersible, there would be no use for them. A bilge pump is used to bail water out of the bilge of a boat using an electrical pump connected to the battery. If the bilge pump wasn't submersible, it wouldn't be able to bail any water, thus defeating the purpose of an electrical bilge pump. Also, since most bilge pumps nowadays are fitted with a float switch (that detects when it should turn on automatically by the level of water in the bilge), which usually activates when the bilge pump is halfway or completely submersed, it is MANDATORY for the pump to be submersible, otherwise it couldn't detect the water level, and it wouldn't be able to bail the rising water level, thus ending up in a boat sitting on the bottom. And what I mean for "most pumps nowadays," I'm referring to "nowadays" as 1988 and up.
I had a non-submersible bilge pump at one point (I tested - it immediately shorted and didn't work until I let it dry) though I think it was intended as a part of a bigger bilge pump or a mount in a specific boat (it was a tiny $5 clearance item). I made it submersible by mounting it on two bricks and putting an upside down OJ bottle over it with holes cut in the bottom to allow enough water in for it to pump (~1/4") but not so much it flooded. I used it as a pond pump for a small water fall for about a year. It was technically not meant for continuous duty but it held up remarkably well esp for $5 and some crash pile junk.
A 5$ bilge pump that's not submersible? It's not a bilge pump if it's not submersible. I learned that all bilge pumps are submersible otherwise they don't work. Maybe you're think about a tiny sump pump?
"bilge pump - A mechanical, electrical, or manually operated pump used to remove water from the bilge." Any pump that can move water can qualify as a bilge pump. Sump pumps, transfer pumps, even manual hand-pumps, etc, can all be bilge pumps. I think we're getting a little too hung up on a technicality here.
Beats me all in all. It was labeled "bilge pump" but I have no idea if that was the correct term or not - as mentioned it was a clearance item so apparently not something that sold well..
Thanks for the information. I've seen manual bilge pumps that look like a bicycle pump and a more compact lever operated ones. If you have a bouncy ride, a bladder with one way valves could pump fluid. I've seen back packs that produce electricity with the bouncing motion, it could pump water too!
by bouncy ride do you mean a bouncy boat ride? Oh no it's all fine, just some 4' whitecaps with a 25' express cruiser. Although I do like the idea of a bladder hooked up to a few check valves, but I don't think it would work because if the ride is bouncy, the water would be moving all around the bilge, and the bladder would really have nothing to push up against, except itself. I'm rather accustomed to my dual-pump system that pumps at about 1,600 GPH. Hehe way oversized IMO.
I want to make a version with the tubes attached to the inside of a vest, so I can ride my bike in cool comfort in this ridiculous Miami summer heat.
Use bubble wrap laminated with aluminum foil that Lowes Home improvement sells for metal buildings to insulate from infrared radiation in the backside of the cooler ....
I'm an outdoor sports photographer in toasty Texas and my body turns into an Olympic-level sweating machine. A backpack cooling contraption could be really, ahem, cool. I'm feeling better already.
Yup, realstick read my mind- cable ties are strong and durable for a lot of applications- for me they're a bonus, because it saves on intricate knots and sewing!
Great idea! A question - did you really mean "350 GPM" or maybe you meant GPH"? My 3/4" home garden hose at full open only does about 5 GPM at ~60 PSI. Another question - do those quick-connects seal the tubing when disconnected? I drive a roadster and keep the top down almost all the time. In summer it's not always comfortable. Your post has me thinking of buying a small $50 12V travel cooler to put in the trunk, then run tubing and switch wires to the cockpit area. A couple of feet of tubing coiled in the bottom of the cooler might do away with the need for "loose" uncontained water. If it turns out not to be enough you could shape the tubing so as to cradle a couple of frozen water bottles That way you could keep a few refreshment bottles cool with the same rig and also not have to occasionally replace a couple inches of icky sloshing water. If you run the tubing over the top lip of the cooler you won't have to worry about drilling and sealing a waterproof seal, just cutting small notches in the lip, then glue foam weatherstripping over it. Only problem is you'd need to use (ideally) a 12VDC self-priming external (not submersible) pump. Looking for a source for those now. Thanks for a great idea!
Yes, gallons per hour. You can get dripless disconnects but they restrict the flow and cost 3 times as much as the non-sealing type. If you're careful only a few tablespoons of water drips at the most. A T at the top of the seat back could let you drain all the water back to the cooler. You can put other containers in the "working fluid", no problem. The bilge pump doesn't have an small input for a closed system, but another type of pump could. Good ideas, thanks!
You could always try cable ties to attach the tubing to the mesh. Might not be especially pretty, nor would it be the pinnacle of comfort, but it's quick, cheap, and effective.
I know I've seen velcro straps that act like cable ties, but are less rigid and reusable. I want to say they were used for bundling electronic cables. They would be just about perfect.
i agree. I have a bunch of Velcro straps and its would be great for this
If you made this w/o the ice (say with cool water stored in the shade of the car), couldn't it be used for longer periods of time w/o complications - and what is the adverse effect of cooling one's kidneys?
If it's too cold, add a layer of cloth, use thicker tubing or a slower pump, I guess. I turn it off for a minute or two if I get numb! Cold slows down the flow of blood & you really need your kidneys working well in the heat. Just being careful!
I'm glad to see this project here. I've been doing something similar for five years now. I keep meaning to post some of my work but every time I make one it seems I get new and better ideas. Plus I just haven't gotten organized enough to put the entire project in one cohesive set of instructions. I have used windshield washer pumps with great success. Be mindful that they must not be run continuously or they will get very hot and burn up after a few to several minutes. I drill the hole near the bottom of the ice chest and seal it well with goop, construction adhesive or even high temperature hot glue. Then I use a layer of silicone glue and as long as you don't bang it around it won't ever leak. If your looking for the smallest, lightest pump that uses the least amount of power you can't beat the Laing DDC pumps at dangerden.com. But you'd better know what your doing with these cause if the pump looses its prime it dies in one seconds time! I used their forums to read up and get links to learn about making a reservoir and such. I am a mailman in Texas and just like a couple of years ago the temperature is over 100 everyday this summer. The aluminum and other metals in my vehicle radiate heat at over 120 degrees and I never get moving fast enough to draw in cooler air. I use a seat pan that is 1/2" thick with about 7 or 8 feet of quarter inch OD copper and an aluminum sheet over that to set on my truck seat. Then I also use the same copper wrapped once around my head overlapping at the back. The trick to both exchangers with direct body contact is to use an interval timer. I usually let the icy cold hit my forehead for no more that three or four seconds at a time. Then the chill gradually fades and I'm ready for another hit twenty to thirty seconds later. If you leave the cold on too long you will feel an ice headache that soon goes away after the chill does. I designed mine this way because I frequently get in and out of the truck and don't have time with hook-ups. Furthermore I must completely add and remove the device daily using very little time. Fortunately we have a nice ice machine at work and I use about four gallons for five hours in the hottest weather. Direct body cooling if by far the most efficient use of ice to keep cool. I've seen the ice chests that blow ice cooled air but I'm certain that one of those just couldn't hang for hours like this setup does. It probably doesn't matter too much which parts of your body you cool as long as there is enough total surface area being cooled. I've read that that should be 1/3 but I'd think in areas with greater blood circulation that can be effectively reduced. One more plug for the good guys. I've been using usplastic.com for all my fittings and square Nalgene wide mouth bottles for making reservoirs. I've also used their Tygon tubing for super flexible tubing but found that to be unnecessarily expensive. I doubt that any other place has such a large amount stuff as they. They may even still carry the Coleman thin cooler which is perfect for setting behind my vehicle seat. They are really great people to do business with. Sorry for being so long winded but for anyone that may want to try variations on what you're doing just realize that if your hands (or feet) are free you can always use a manual pump. The hand squeeze bulbs sold in the boating section or even large "hand lotion" type pumps actually can pump enough water to replace any motorized pump. This might be a really budget way to test direct body cooling before investing lots of time and money into a project. I've actually used just a two quart insulated water jug, the hand lotion type pump and just enough copper tubing sewed to the bill on a cap to use while mowing the yard. When you keep your forehead cool you don't sweat there. So instead of using energy to wipe the sweat from your head, just use your other hand to pump every so often. It is my greatest hope that someday truly light and portable devices will be made available for people that have to be in extreme heat. Probably someday far in the future everyone's clothing will do that. It's the people like here at instructables that pioneer new ideas that might otherwise never see the light of day. So I hope that others will be working on cooling such as yours and together come up with some really great ideas. And I too will be posting one of mine here before too long.
Oh, the first pump I used was an in-tank gasoline pump from a car. It worked well until it rusted, about a week. Made to pump gas, not water.
Lots of ideas, Veetron! I hadn't considered the CPU cooling technology. Good source of fittings! How about bladder insoles to keep your feet cool and pump fluid while walking?
Fantastic. I'm always hot at work - I'm going to use a submersible fountain pump and adapt this for the office. Some twisted tubing is probably in order...
Good idea. Here's an idea, color the fluid and then meter air into the tubing. Use clear tubing and you'll see the fluid flow.
Could you cut a path out of a seat cushion for the hose to lay in?
Sure, or if the seat cushion is soft enough so the tube isn't crushed. The tubes work best with one layer (or no layer) of clothing, and it helps to shift around a bit while it's on, so the seat bottom isn't the best place for the tubes. But if it works for you, let me know.
I was more thinking of one that could be on your back. I see the problem though if it works best with bare skin.
wonderful idea, thanks for the post. You have made the gerbil rabid and the squeaking from it's wheel running in my head is giving me a headache! my thought is to place the tubing from the cooler into the tubing in your cars air system, that way whatever temp the air is in the pipes is the temp for your seat back. though i have not troubleshot this plan yet. this would cut down on the fan noise running the system at full tilt boogie on a hot day.
This would be ideal for electric vehicle conversions. I notice your name is Ev. Did any of these cooling devices you made go into electric vehicles?
Yes, my cousin has one in his VW Ghia conversion, which has the running gear from an EV I owned, a '73 Thing. I've posted the basic idea on the EVList over the years.
With a smaller pump and water container, this could easily be made into a backpack design. :D
A backpack design would work and you could attach the tubes to a shirt. Even simpler? Put frozen ice containers in a pack or strap 'em to your body, then as you need to cool off, pull insulation away from the container.
Another thought I had was this:<br/><a rel="nofollow" href="http://www.antiyawn.com/guidetocarfridge.html">http://www.antiyawn.com/guidetocarfridge.html</a><br/>It's a DIY car fridge! Hook everything up to that and you have a smaller, more efficient cooler.<br/>
I seem to remember that some or other kid who's body lacked the cool down thermostat had a portable one made using a type of waist coat that had the pipes in it and the water was pumped over freezer bricks / cool box ice bricks that were in pockets on the sides. I think 2 of those big bricks lasted him half a day or something surprising like that.

About This Instructable




More by Ev:Too Hot? Keep cool at home, car, outside with the Back Cooler! 
Add instructable to: