Solid Fuel Swimming Pool Heating

[vortex2]

Hi,

After much pressure from children I am seriously looking at getting a

low cost above ground swimming pool.

The Sister in law purchased one 5 years ago and I have to say in terms of £ / unit pleasure / year it's been very good value....though it's now at the end of it's life.

The main negative is that it's darned cold. Children seem relatively immune, but for me the temperature removes the fun.

I am however the proud owner of a HUGE pile of oak logs after some recent tree maintenance. I reckon there are multiple Gigajoules of energy therein.

Any suggestions as to how to transfer this energy from logs to pool? It takes the edge of a G&T when your body core temperature gets too low.........

My thoughts:

2nd hand log burning stove with back boiler > Indirect HW tank > pool. I have however been told in the past that it's not good to have pool water passing through copper pipes. Something to do with ions !?!?! Is this true or is it horseshit?

Any other ideas or suggestions?

(BTW I have a Solar plan too)

D

[Dave Liquorice]

Well that pool 15' dia by 3' deep roughly has about 5,000l of water in it. So you need 5,000 x 4.18 = approx 21,000kJ of energy (6kWHr) to raise its temperature by 1C (in 1 hour) but that is *not* taking into account any losses. I expect the losses from such a pool are going to be quite high... and you're going to want a bit more than a 1C temp gain.

So you want a swim in water at 15C (slighly warmer than summer UK sea temp) starting with water at 10C and you are willing to keep the wood burner stoked and burning well for 5hrs. Lets assume 50% losses, I wouldn't be surprised if they are higher mind...

Energy is 5000 x 4.18 x 5 x 2 = 210,000kJ over 5 hrs = 42,000kJ/hr or roughly 12kWhr, that is quite a large but not impossible wood burner. But it will need feeding fairly frequently over that 5 hrs to maintain

12kW output.

Google back in here to last year? A couple of threads about solar pool heating, seemed to be pretty cheap and very effective. The power levels are no where near as high as the wood burner but lower levels for much longer periods and without effort have a lot going for them...

[bigcat]

Solar will give more heat for far less trouble and far less expense. It really is the way to go with pool haeting. All you need is a huge length of plastic pipe and a pump. And for greater output, some ali foil.

Lay ali foil down Coil pipe into a huge coil, but with a pipe's width space between every turn. The combination of this spacing plus the ali gives a lot more output per pipe length)

Add pump, away you go.

But before heating it, it would make best sense to stop throwing all the heat away and fit a pool cover.

NT

[Holly, in France]

You might be surprised how quickly you get through the huge pile. We heat our house all the time with oak, woodburners get through an enormous amount.

snip rest of useful stuff. Just posting to say that I am currently researching this too, and I also have vague ideas of trying use a woodburner to heat a sauna and provide some heat for a pool. I'll post again if I get anywhere with it. Don't go away Dave, I'm impressed by your sums :-) If by any chance anyone has ever had a combined sauna/pool system heated by a woodburner, do tell....

Holly, in France. Holiday home in the Dordogne, website:

[Mike]

Cover pipe with polythene sheeting to retain heat ... then

Also replacing the ali foil with something like Airtec or thin Kingspan will avoid heat loss to the ground.

[bigcat]

expense. It

Kingspan will

Those would be advisable for DHW solar panels, but counterproductive for pool haeting panels.

Pool solar panels operate at 2-3C above pool water temp, so covering with poly would block out more light than any losses. And insulation underneath would achieve nothing. Better to spend the tenner on more pipe.

NT