Jack Moore - Product Designer

2016

I recently bought a book called "Cabin Porn". Unsurprisingly it is about people building cabins all over the world. Many focused around a simple way of life, self sufficiency, living off the land around, or building with no real experience and learning on the go. One of the first images in the book was a double page picture of some people in a wood fired hot tub which when I saw I thought to myself “that looks amazing!”

 

They had built it next to a stream by their cabin and filled it up each summer from the brook. It took them approximately 2 hours to heat the water to 40 degree celsius. Not only did I think to myself that looks amazing but also “how can I make one of those?” I began some research online and became fixated with trying to find out how wood fired hot tubs worked. To my surprise there isn’t a lot on the internet about them!

 

Eventually I found a mildly informative video on YouTube of someone who’d made a wood fired hot tub and so decided to use it as a rough guide for my own design and build.

 

Unfortunately there isn’t enough room in my own back garden for a hot tub, plus we’re a little too overlooked by neighbours to want to run in and out of the house in just our swimwear! So I asked a friend of mine if I could build a wood fired hot tub in their back garden?

 

The ultimate challenge I was setting myself was to build the hot tub so that:

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a.    it worked, otherwise my friends would have found themselves with a very large bucket in their garden!

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b.    it cost less than £50.

 

The build began with a bulk liquids container that I sourced from eBay for £20. This gave me a watertight container surrounded by a metal cage which acted as the main structure for the hot tub. I’d also managed to get hold of some free pallets to use as cladding for the outside of the container so as to make it look far more attractive.

 

Making the heating element of the hot tub was the biggest challenge and where I had to do the most learning. This consisted of an old gas canister in which I had to cut a door and was to act as the wood burner. Inside the gas cylinder would be a copper coil through which cold water would be fed. The water would then be heated up by the fire below sending hot water back into the tub. The copper coil was made from a 3m length of 15mm pipe which I packed tightly with dry sand. Prior to use the sand had been dried on mums baking sheets in the oven and carefully sieved. This was to ensure that the sand could be easily removed from the coil and did not stick to it. The length of the pipe meant that it had to be filled using a funnel from my brothers upstairs bedroom window. The ends of the pipes were sealed and a coil formed using an old chimney pot that had the right circumference. It was a great relief that this was achieved without damaging or kinking the pipe. 

 

The gas canister was purchased on eBay for about £6 with the copper pipe bought from a hardware store costing aproximately £15. Other small fixtures and fittings for the project cost around £5.

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The entire project took me about two weeks to make and when stepping into it for the first time there was much relief as I felt warm water against my legs suddenly bringing on the realisation that I had managed to make a fully working wood fired hot tub for under £50 and not just a big bucket!