Diy pool heater from spare parts

[Antmp]

Right first befor anyone tells me im mental this is basically and idea using parts iv pulled from renovation jobs iv done just to see it would work...... and any constructive input is welcome.

So iv bought the kids a 3 x 2 x .75 pool nothing massive but where i live in the uk is not the warmest nw uk... iv had an idea to use and old water tank as a heat exchanger linked to an old combi boiler converted to run on propane. The reason for propane is 1 not to have to run a has line out to the garden. 2 so i dont just leave it running up my gas bill after a few drinks.

The idea is to conect the central heating loop to the water tank loop and then pump the pool through the normal water feed on the tank.

This also lets me run and electrical element in the tank conected to an inverter on a battery bank.


As i said i know this isn't perfect its just a fun project using parts i already have

 

[Agile]

All of the commercial pool heaters use a wide bore high flow pool water.

Although in theory I would expect your idea to work in practice it is likely to have a serious problem.

That is if you add any chlorine chemicals to your pool as are done with large pools then they are likely to cause corrosion problems with a copper cylinder.

I think that a few plate heat exchangers with the pool side in parallel and the boiler side probably in series or series parallel would be a better bet.

A car battery has a capacity of about 1 kWh and that would run a 3 kw immersion element for about 20 minutes! And thats with a new full capacity battery. So I do not think you will want to even try that!

A better and cheaper alternative might be to make up some solar thermal panels from some old radiators with loft insulation behind. You do not really need to fit glass over the fronts as it is only likely to be used during warm summer weather. If you did want to fit glass then clear plastic would be far cheaper and easier to fit and not get broken.

 

[Antmp]

Yes i was worried about the chemicals being an issue. But it wouldnt be getting run constantly and its more just an experiment for a my nerdy self to play with. Iv even gone as far to collect 6 inch thick sheets of insulation from a walkin freezer i replaced so i can totally suround the the pool on all sides befor i build a deck around.

 

[oldbutnotdead]

The chemicals could be an issue as above. The efficiency might be a bit grim (32 degrees water temp ish for a pool), you'd have to make sure circulation from pool to cylinder was running continually so you don't get a blast of properly hot water, possibly incorporate a (cold) makeup tank with a TMV for belt & braces scald prevention.
If you only put half a metre of water in there you're still looking at 3000 litres, without some proper chemical treatment setup going on you could end up with a nasty Legionella-filled soup (bacteria love the warm). Final thought- will the pool get too soft & fall to bits?

 

[Agile]

I certainly agree that the pool needs some water treatment. Both for Legionella and anti algae.

Even such a small pool has a long warm up time and I have always imagined that if I had anything like that then I would heat in the early morning before the house needs any CH or HW and that would get over any slug of hot water.

Although if I was dealing with an anti slug then I would feed the flow into a larger open ended pipe to premix with the pool temp water.

 

[Antmp]

Oh ill definatly be treating the water i think i see what temprarure i get when its totaly insulated and has the lid on it im not trying to get it to hot tub sort of temps just that extra few degrees for the kids.