HillBilly Hot Tub

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Introduction: HillBilly Hot Tub

Here in the UK it's been a great summer and I thought it would be good to relax at the end of the day in a nice hot tub. Trouble is they are quite expensive to buy and run and you need power and chemicals and really how many times would you use one. So I decided to build a low cost hot tub which can be run off grid and can be used quick and cheaply to have some fun. 

Step 1: Materials

Knodd 40L bin with lid from your favourite Swedish bin emporium. £15 25 m 10mm micro bore central heating pipe from any plumbers merchants. £ 40 Kids paddling pool - I got a 1.9 m pool from Argos at the end of the season for £30 Aquarium 8mm tubing for pumping the water round your coil. 12v pond or bilge pump to circulate water. 12v power source - a car battery is ideal .

Step 2: Construction

The beauty of this is that it is so easy to make. We only need to construct our heat exchanger inside the metal bin in order to get tubbing! If you go with the Knodd bin you will see that it is tapered. This allows us to use it as a nice former for our heat exchanger. Start by drilling a hole in the side of the bin and insert the end of the coil from outside to inside the bin. Then start turning the bin smoothing the coil tight against the outside of the bin. After a while you will have a lovely shiny heating coil.

Step 3: Get Ready to Soak

Now you have your lovely coil you need to get it inside your bin. Since it is tapered you can take your coil and slide it inside the bin with one end poking out of the hole that we drilled to start. The top end you need to drill another hole and poke the other end of the coil out. You now have a cool portable hot tub heat exchanger. Now with a couple of flexible plastic tubes on the ends of your pipe you are ready to fire up your hot tub.

Step 4: Fire in the Hole

Now we are ready to crank up your hot tub. Fill up your hot tub with a hose - the one I had was around 700 litres and took a couple of hours. Get your pump and put it in the pool, connect the outlet of the pump to the bottom pipe from your bin - this is the hottest part of the burner. The outlet just flows back into the pool via your return tube. Careful it could be hot ! Get a nice hot fire going - your pool will heat up in around 4 hours if you keep your fire hot . Once it is up to temperature (I like 40c) you can damp the fire down with the lid supplied .

Step 5: Find Your Perfect Spot

So the benefit of this tub is it is portable - you can put it anywhere you have some water and a flat space - I have the perfect spot under my cherry tree. You can see the pool and pump fits inside the bin so its easy to transport. Enjoy with your friends our your favourite drink - mine is an Innis and Gunn :-) Have fun !

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    24 Comments

    0
    TheThermoSiphonGuy
    TheThermoSiphonGuy

    Tip 10 months ago

    The beauty of an added pump will heat the water slightly quicker, but really not much. The pump also prevents the water from becoming high temp steam in the coil. Really no batteries or pumps are needed if you have a drain plug on the bottom side of your pool if you use purely thermo siphon principals. In my design, I took a used old cast iron bath tub. Hook the drain to the inlet and bottom of your coil. Ideally it's better if your thermo siphon sits lower than the water vessel itself so you get some help from gravity. The water will naturally drain into the coil otherwise and the heat will draw the colder water into it. The top of the coil and outlet -- make sure it is slightly below waterline in your vessel. Prime the coil with a garden hose to make sure there is water in your coil when you start your fire. Sit back and wait. It will take roughly 4 hrs to get hot tub hot depending on outside air temp, insulation of your tub, and whether you have a lid. WARNING: Advisable to tie cloth around or shroud the outlet end of your pipe if you have no pump in place. Your hot water will come out of the coil as very high temp steam which can obviously burn you if you don't heed the warning and use some common sense. Always keep a couple buckets nearby full of cold water in case your water gets too hot, or your fire escapes your burn chamber.

    0
    astuart4
    astuart4

    4 years ago

    Question, just looking at those pumps, did you use a fuse between the pump and the battery?

    0
    popsicletoes
    popsicletoes

    4 years ago

    Wow! might try this modification on what we did. For my birthdays I like to go camping but I also love our Japanese bath so for a special birthday we did something like this but for heat we used an old Zoti water heater for use on propane camp stoves similar to this :

    http://www.hotcampshowers.com/inc/sdetail/484

    by recycling the water through it and supplemented it with pots of water over the fire. Your way though you don't need to use a lot of propane so I like it better (although copper tubing is way pricey now). Either way though it was the best soak and we covered it with pool cover cut to fit and were able to use it again the next day (just wash first before you go in as with Japanese baths)

    0
    waggy101
    waggy101

    7 years ago

    I mean i know that my money value is 2• what yours is but it would make it easyer

    0
    waggy101
    waggy101

    7 years ago

    Nice but, could you convert in ( ) american money value?

    Try a homemade it reflector above the tub. line the underside of a garden parasol etc with reflective aluminized snack packets, Dorreetos are among the best. They are much more durable than space blankets. It DOESN'T need to be in contact. I promise you will be amazed. john

    0
    stonky
    stonky

    7 years ago

    Great idea many thanks

    0
    bginlalaland
    bginlalaland

    7 years ago

    Love photo of the coiling process and your little dog looking at the camera. Too cute :^ D

    0
    Ole bally
    Ole bally

    7 years ago on Introduction

    Great Idea, now for a 'mod'! If you were to cut out most of the bottom of the bin, leaving say a 1" rim inside, you could put a stout mesh inside. Put the bin on a coupla bricks. Then as your fire fuel burnt to ash, the ash'd fall out the bottom making yr unit self cleaning!

    0
    Ole bally
    Ole bally

    7 years ago on Introduction

    great idea! Now a little 'mod' for you! If you cut the bottom out of the bin and put some stout mesh in there, you can stand yr bin on a coupla bricks and as the fire burns, the ash'll fall out the bottom...making it self cleaning!

    0
    BumbleBzNjellyBns
    BumbleBzNjellyBns

    7 years ago

    this is a awesome. we were without electricity for 10 days year before last and my husband and I took ice cold showers. gonna make one of these for emergencies as well!

    0
    BumbleBzNjellyBns
    BumbleBzNjellyBns

    7 years ago

    this is a awesome. we were without electricity for 10 days year before last and my husband and I took ice cold showers. gonna make one of these for emergencies as well!

    0
    richiemcb
    richiemcb

    7 years ago on Introduction

    In the UK we sometimes like the off grid Hillbilly lifestyle :-) - but the heating coil is the same design as a Hillbilly Moonshine still.

    0
    Wifflechicken
    Wifflechicken

    7 years ago

    you have hillbillies in yhe UK?

    0
    rhathaway
    rhathaway

    7 years ago

    Cool idea and I too love innis and gunn my personal favorite is the rum cask.

    0
    richiemcb
    richiemcb

    Reply 7 years ago on Introduction

    Thanks ! Nothing better than the rum cask - very smooth and just right for soaking your cares away :-)