Instructables
Picture of Camping Hot Tub

Sitting around the camp fire at a lake has left us too hot on one side and freezing on the other. 
Drunken idea - A hot tub would keep us warm all over. 
It would also get the girls in thier bikinis!
How will a 10x10x2ft body of water be heated and kept hot? 

Don't forget to comment, rate and share! :D

Caution!

This intsructable is how to build a Camping Hot Tub and is for entertainment purposes only. 
Safetey first!!! It involves power tools, fire, electricity and water.  Recreation can be very dangerous.   
I am in no way liable for anything you do, damage to vehicles or equipment,
loss of life, accidents that may occur, fines incurred, acts of god, etc.
Leave it the way or better than you found it! Clean-up and don't start a forest fire!

DO NOT CUT DOWN TREES!

Goals:

Transportable hot-tub equipment.

Tools:
Chainsaw
Shovel
car/truck or Generator

Materials:

Tarp 20x20
copper coil 5/8" OD. (outside diameter) @ 100 ft.
hose 5/8" ID. (inside diameter)
hose clamps, Get more than you need!
Washers
Power Inverter
pump 1/12 hp utility continuous operation
Large pond pump
large hose
Rocks (should be on the beach or in the river)
strong metal baskets (look around at thrift stores)
 
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Step 1: Location

Picture of Location
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Find a really awesome camping spot. Either near a lake or river preferrably within 100 ft or less. Send the minions out to gather wood for the fire. The more the better.  We burn a utility trailer load every 3 hours.

The tub needs to be close so it can be filled and refilled as needed.
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blomeclown3 years ago
Great instructable although I wouldn't try it. Not because it's a bad idea or dangerous or destructive to the environment (all comments that have already been made) but because my idea of roughing it while camping is when the pizza delivery is late to a 40 foot Airstream trailer.
This is aimed at the commenters who post the "I would have done.........." or "You should have..........." comments, NOT at the ones who post the "I made one of these but I........" comments. You know who you are and you know what the difference is. Player2756 had an idea, worked on it and did it. If you think you have a better way, post a frakkin instructable. Just give Player2756 some credit even if you disagree with his methods.
There were several comments made about the extra work that may have been needed to make this tub the way it was made. So what?? I can't think of a better way to spend time at a lake than to work your butt off doing something and then relaxing with a cold beer and some cuties in a hot tub. Kudos, Player.

This man gets it.

hogey743 years ago
OK this is awesome. I am promoting you to honorary Australian. You just need to let off some illegal fireworks or develop a new type of spud gun and you can be a full citizen.
player2756 (author)  hogey743 years ago
Thanks mate!

hahaha 'mate' - gotchya

hogey74 adodds15 months ago

:-)

... and 3 years on, this thing still rocks!

yerdadh8sme3 years ago
You sir are my freaking hero! That is AMAZING! Now if I can convince my fellow campers to help me do this we will be in business! I literally just set up an account here so that I could thank you for this idea.
player2756 (author)  yerdadh8sme3 years ago
Its lots of work but is fun at the end of the day!
spaztec3 years ago
I applaud the pot-of-fire. It made my day.
raygris3 years ago
Hot rocks can work fine. You do have to choose your rocks (smooth, hard, no cracks) This method has been used for centurys in sweat lodges.
Anouther method:
A friend of mine used his truck as the pump and heat source for a portable carnival "dunk tank". The tank was an old wood hot tub.
He diverted the radiator hoses to a scrap radiator that was submerged in the tub. Quick and easy. One person setup. 2- 2.5 hrs start to tubbing.
.
klarsen-crisp2 months ago

has anybody ever used a coil on top of a propane camp stove?

OurPantheons2 months ago
Dudes! I so have to try this. Thanks for the awesome idea and instructable.
timbit19853 years ago
Using a small rocket-stove type setup with heat exchangers in the combustion chamber would be more efficient :)

I've been working on a very similar project, only using an 8' above ground pool (650 gal) as the camping hot tub. They're relatively cheap, easy to transport, and quick to set up. My first attempt to heat it was using 50' of 1/2" dia coil placed directly in the fire, as is shown here, and I ran water through it using a 1/6 hp submersible pump run off of an inverter connected to my car. It took a loooooong time to heat, probably 7 hours, and we went through a tremendous amount of wood. It was fun, but not practical anywhere that you'd need to pay for wood. $$$!! We were lucky that there was an abundance due to a landslide in the area a few years before. My next attempt was using a homemade woodgas stove with a heat exchanger just above the combustion zone. My goal is to heat the tub using pellets, which are cheap and easy to deal with. Details of that build are irrelevant, as it worked great in a batch type burn, but would fill with charcoal for the longer burns required to heat this much water, and turned out to be too annoying to deal with. Refilling it was a mess and would drastically effect the flame, very inconsistent temperatures resulted, and intermittent big black clouds of smokey unburnt fuel would be lost out the chimney. My third attempt was using a rocket stove with a heat exchanger on top. With a 6" diameter burn chamber, 4 x 50'x 1/4" diameter copper coils in the heat exchanger, everything veeeeery well insulated, the system converts about 40% of the potential energy of the pellets into water heat in the pool. I think it outputs a real water heating value of about 23,000 Btu/hr into the pool. Which i think is pretty decent for a portable homebuilt system. It resulted in a 9 hr heat time, and only costs $1/hr to run, and produces almost no smoke so you know you're not wasting any of your fuel. 9 hrs is still waaaay too long though, that's a whole wasted day. (A side note: there is massive restriction in 1/4" copper tubes, even having 4 plumbed in parallel caused a big reduction in flow. I wouldn't recommend going this small.) The rocket stove was well behaved though, and the concept seems to work well. To get the heat up time down to a passable 2-3 hr range, I think you'd need a rocket stove with about 400% of the output of my 6" diameter system. I haven't built or testing the next prototype yet, but I'm thinking it should be a rocket stove with a 12" diameter burn chamber, which according to simple math should get me to 400% increased output. I haven't figured out how to build this yet, so can't offer any advice there, but according to my tests, and the math, this seems to be the size that would be practical for this application. I hope someone out there find this info handy, it's taken months of meddling!

player2756 (author)  timbit19853 years ago
I would love to read about/see it in your Instructable.
Misleib6 months ago

I once made a very similar project but was able to simplify the water heating process greatly. I connected my hot tub to a 55 gallon drum that was over an open fire down hill from the tub. The connection of the pipe to the drum was at a low spot on the drum so that as the water boiled the steam would rise and push the water out of the drum and into the hot tub. As long as you didn't put a hand or foot right on the pipe there was no real danger of getting burned as the water was entering the hot tub. After all the boiling water was pushed out of the drum the steam would escape and the pressure would equalize. Water would then start to run down the pipe and cause the steam to condense. This would cause a powerful suction that would refill the 55 gallon drum starting the process all over again. It would take about 5-15 minutes for the cycle to repeat depending on the intensity of the fire. Sometimes the water would not flow back into the drum to condense the steam so a quick splash of water from the hot tub to the outside of the drum would be required to start the cycle again. No pump, no carrying baskets of rocks, limited plumbing and the fun of waiting for the next cycle to take place. I called it the geysertron because of its similarity to the process of a geyser shooting out boiling water.

Misleib Misleib6 months ago

I forgot to mention that this design did require the inlet to the hot tub to be at the bottom of the tub. A hose over the top of the tub would not allow the water to flow back into the drum through gravity. The splash technique mentioned above would still work though if you didn't want to put a hole in your tarp and seal the opening.

jonathondk1 year ago
I wonder if you wouldn't be able to get a fire powered water pump or something along those lines so you wouldn't need the car...
Stalker3 years ago
I would personally not advise the hot stones method. Rover stones, that have been submerged in water for some time tend to retain some of that water inside of small cracks etc. Once heated the water could be turned into steam too rapidly for it to escape, causing the stone to explode.
That depends on the kind of stone it is, sandrock is the one that explodes. Other stones should be fine
they are not the only one - i use to pull all kind of stone out of a creek - and they all blow - long story shot don't get them out of the water
Mike44 Stalker3 years ago
Hmm, exploding stones? That's a new one I have yet to see!! Theoretically, it makes sense I guess...

Neat idea with the hot tub though!
JermsG Mike443 years ago
Yep. Seen it happen... exploding rocks are LOUD! Luckily I haven't seen anybody get hurt by them yet.
pfiddle JermsG3 years ago
I spent time in the Sahara Desert - camping. Just myself and girlfriend in 1978/9. In the afternoon - around 5 we'd - have to find a sandy spot (NOT as easy as you think!) to pitch our tent. If we weren't in by 6 there was a good chance we'd freeze to death as we didn't have the appropriative clothing. Lying snug in our eider-down sleeping bags we' be kept awake for up to an hour as the rocks exploded all around due to the rapidly falling temperature. We were warned many times not to go out at night except over sand because of this - and the fact that the scorpions and snakes come out at dusk from under the rocks. It was particularly bad in the area of Taminrasset in the South of the country.
As I've stated earlier use igneous rocks - or suffer the consequences.
adawg67 Mike443 years ago
Happens all the time with rocks out here in S Cal-We use smooth river rocks when that's all we can find to build a fire pit and dang if a few of them don't blow after a few fires. It's more about the cooling off process I think much like glass blowing- the cooling off has to be slow enough to not create significantly more heat inside the rocks than on the outer layers.
sugarsnout2 years ago
AWESOME CAMP LUXURY!!
bus lady2 years ago
Um for what it's worth with the whole hot stone thing. DONT PUT RIVER ROCKS INTO THE FIRE!...and generally your good. Same is probably true for ocean rocks. There can be little pockets of water in them that expand and explode.

I grew up making saunas in the woods (putting rocks in the fire, moving them and then pouring water on them in some form of temporary shelter.) That rule never did us wrong.
I read in a book called 'Cabin Fever' about a solar water heating system that used flat black painted copper pipe in a 4" deep frame with a glass cover. Instead of using a pump he put the top end outlet pipe to just below the surface of the water and the bottom inlet to the bottom of his tub (actually it was a horse trough) . The heat stratifies in the water pushing it upwards and starts circulating all by itself! I'm definitely going to make a mini version of this and use a 5 gallon bucket, then attach a shower head to it. Oregon's not a particularly sunny place this time of year so it'll take awhile before I can test it. So keep a look out for my first instructable soon. Thanks for the idea and happy hot tubbing!!
fzbw9br3 years ago
just get an old 30lb propane tank, using all necessary precautions, make a top fill stove out of it with a wide base, and set it in the middle of the tub, add wood and light.
you control the temp by the amount of wood fire
nice! someday this will be the starting point I build upon. Hope to have an 'ible on in soon! :)
mvanduker3 years ago
Nice, I have been doing this for years. It's a lot of fun.
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Nice, I have been doing this for years. It's a lot of fun.
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this looks a lot more efficient. can you post an instructable of this? or explain how to make the coil?
player2756 (author)  Houdinipeter3 years ago
looks about the same but with some spacers. The reason I didn't use spacers is because of differing melting points and general heating and cooling.
sbrown13 years ago

Great...
you could try and use a secondry heat exchanger, as in what a combination boiler uses.

then you are not going to open up the system on the car/van each time to use it, your just going to tap onto the heat exchanger.

im a gas engineer and it is whats used in combi boilers to heat up the hot water in your home.
player2756 (author)  gareth.collier.19853 years ago
Like this?
http://www.industrial-boilers.org/wp-content/uploads/2010/07/boiler-heat-exchanger.jpg

I will probably do a revised ible this upcoming summer some time, maybe end of winter, that will include something like this.
no that's not it, that works in the same way to using the copper tube in the fire.

i cant find a diagram at the moment to show you, and i am no good at drawing on a pc to show you either.

the closest thing for you to look at for the idea is a hot water cylinder.

if you where going to try this, i would reccomend getting an industrial heat exchanger as it will have a bigger flow rate and you dont want to over heat your car because it cant dump enough heat quick enough.

sorry if this is confusing for you but i do find it hard to explain things in general and worse at 3am.

good luck and as long as there is enough heat in the cars radiator fluid, then this would work, or at least get it to a nice warm temp.
so you get the idea ( i hope )
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nerd
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