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Solar heated spa pool

Me sitting with mates in my home-made hot tub on my birthday :)

How to Build your own homemade spa pool

It's dead easy, you just need to collect a few things.
I choose to buy a plastic water trough, but often 2nd hand spa baths, or spa pools are actually cheaper...
Then as things got more complicated I ended up needing more stuff. Here is the list and prices :)

$350 675 litre polythene water trough
$200 200m of black 15mm polythene pipe
$130 Water pump
$100 "Chippy" water heater fire
$50 Copper Plumbing pipe & Chimney & Cowl
$50 Lots of plastic plumbing fittings
$30 Spa pool cover

The Total cost of this project has been ~$720

Not bad for a home made hot tub, primarily powered by the sun :)

First you need to go to your local farming supply shop, and buy a plastic water trough.
Place this in the corner of your garden.
Next get a mate to come around, ideally a strong guy, and get them to climb onto your roof with the 200 meters of black polythene pipe also bought at farm shop.
Promise a few beers for your friend and they will work harder....
Now, sit back, relax.... let the sun warm your water :) 
The finished solar spa.
Well this was mark 1,
and worked OK in mid summer.
To get it to work in the middle of winter,
I added a fireplace specially designed for heating water.
Now things began to get more complex. The fireplace needed to be below the top of the water level in the spa, I also needed to find someone who could gas weld the copper pipes.

I needed to trim the trees to allow for the chimney, and I started to think about insulation for the trough, hence the re-cycled AstroTurf under the hot-tub

Then I bought a water circulation pump, and wanted to protect it with a filter. This was the first attempt at a home made filter. Made by "sewing" a coffee plunger filter onto the outlet pipe fitting using thin coper wire that was lying around in the shed.
Homemade filter mk2 used 1mm stainless gauze. This fixed the problem found on the first trial-run. The gauze from the old coffee plunger filter was too fine and the pump was struggling against a buildup of Didiymo!! You can see the fine gauze above, and the new filter being "sewn" together.
Building demolition sites are a great source of free wood and other random finds.
This is where I got my hot tub insulation from... for free :) These pink bats were a bit dusty but otherwise in great condition. Yey.
After wrapping the tub in enough plastic to fold down over the bats, they are placed and tied in place.
The standard size bats are perfect, no cutting is required :)

Here you can see the completed pink bats insulation. The bats have been wrapped around twice, with the 2nd layer staggered to ensure no gaps and thus optimal insulation. The plastic was then folded down over the top and tied in place with more string. 

The newly insulated spa is a great success !!

It holds it's heat very well from day to day,

and is very, very relaxing :)

I've now had time to redesign the solar heat collector :)

As you can see below it's a big improvement over the first version....


The clear cover allows the energy from the sun to pass into the solar hot water panel (it does this as visible light)
This visible light energy is changed into heat energy when it is absorbed by either the black pipes, or the black background inside the panel.
So the whole inside of the insulated panel including the air gets hot, and then the water pumped through the pipes in the panel takes this heat away.


It's really that simple, sun shines light in, panel gets hot, pipes take heat away :)


These mods have drastically reduced the need for the chippy. Now I only use wood to heat the pool in winter.
I'm very happy with my homemade solar hot water panel !!

The only one slight problem is now i want MORE heat, MORE power !!!
I don't want to need use the chippy at all. I want an entirely solar hot tub all year round.
The solution - just build more of these simple and very cheap panels :)

Soon I will build two more panels the same as the first....

Follow this link to the complete instructions for how to make a homemade solar hot water panel

homemade solar hot water panel

Free hot water from the sun for a one off cost of about NZ$ 60

Copyright 1997-2013 by Anthony Field on all images/text/information and graphical materials on this website.