Too Hot? Keep Cool at Home, Car, Outside With the Back Cooler!

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Introduction: Too Hot? Keep Cool at Home, Car, Outside With the Back Cooler!

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

Materials:

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

Tools:
Drill & bits, 5/32"
Knife
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.

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    user

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    59 Comments

    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!

    1 reply
    user

    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

    1 reply
    user

    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.

    I made a similar set up only I used 1/4" 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!

    1 reply
    user

    R,
    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.

    -Ev

    i read that some air dusters contain difluoroethane, maybe it can be used as a refrigerant for a DIY system?
    or the liquid itself might be used for cooling

    1 reply
    user

    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?

    4 replies
    user

    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.

     yeas auctually i am using pods in my "prototype"... 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 20ºC, 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.

    user

    Had a question about the quick release connectors. I used Colder part number APC22004 and APC17004 from www.US Plastics.com.

    user

    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.

    2 replies

    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?