The Monday Experiment
Today’s experiment involves learning how much heat comes from a little plastic panel!
Now of course this will be old hat to those who have done this before but apart from heating up the hosepipe in the sun this is as near as we’ve gotten to heating the hot tub. What you see above is a plastic sheet with tubes in it, a small 12v pump, currently running off a battery but will be run off the sun (that side is already sorted – I have plenty of spare power) – and a bucket full of water.
The idea being if the sun is up, the pump works, pulls water from the hot tub, pushes the water through the black panel and back to the hot tub. As the latter is currently empty I used a bucket and just as well as I forgot to ensure the pump was able to handle a decent head of water – that is the height from the water supply – to the pump. Well, it can’t handle much. A better pump might be needed. However, generally speaking it works with hardly a murmur and within, what, 20 minutes or so, the 3/4 full bucket contains very hot water indeed.
The pump came with 3/4” fittings while the panel came with drain-pipe size fittings – thankfully the local hardware store (Cullar) had all the bits I needed – and cheaply.
So there it is – you can feel several degrees change on each iteration through the panel – of course the hot tub contains CONSIDERABLY more water – but if it takes all day so what.
Days later an update – the pump is now running off solar (i.e. sun goes down, pump stops, sun comes up – pump starts) and the heat hitting that black panel is raising the temperature of the hot-tub to over 36c – for free!! and yes, it is somewhat neater now though still waiting a permanent wall mounting.