new diy solar water heating project for above ground pool - advice please?

[barnsley]

I’ve just bought an above ground 12ft swimming pool (1700 gallons) and I’m researching how to build a solar water heater for it.
Here’s what I’ve got so far:

My environment (uk average sunshine hours in summer 7hrs and average temp are less than 70f (under 20c).
I would like to put a solar contraption on my shed roof which is right next to the pool (shed is 7ft high).


Pump
Standard pump which came from the pool (300 gallons per hour / 1300 litres or 1.3 cubic metres p/hr)

• Not sure what kind of power I need for this job?

Solar material:
Polycarbonate multilayer 10mm, 25mm or 35mm thickness? – not sure if there will be much difference between the 2?
I was told that the Light transmission for 35mm is 63%, and 82% for 10mm (don’t know what that means in terms of water temperature?).


Dimensions:
I’m thinking of something like 1metre x 2 metres.

Pipe:
Regular black hose pipe 100ft (30m) x half inch (10mm - 12mm).

• Not sure if I can get some kind of connectors to connect a 10mm hose to my pool hose which is 32mm?

Any advice welcome, thanks.

[J.P.M.]

Check out a site called builditsolar.com. Lots of ideas.

Easier, better, more efficient and less hassle than DIY: Solar panels designed for the purpose. It'll cost a bit more up front, but still mostly a DIY job w/ less hassle and time, and better performance. You'll need something like 50 - 75 ft^2. 4 ft. X 10 ft. is a common panel size. Start small, 1 or 2 panels, plumb the panels in parallel and make the plumbing flexible for expansion. Bump the array size in 1 panel increments until the H2O temp. is suitable.

Before any of that, get a pool cover. They are about as effective as a solar pool heater if used, and often mitigate the need for a heater, or at least lower the additional heating requirements ( read less expensive).

[Logan5]

I agree, a cover is first and foremost, If you must DIY, spend time, reading the stickies in the solar water heating forum. there is much to learn about materials and techniques

[J.P.M.]

I agree, a cover is first and foremost, If you must DIY, spend time, reading the stickies in the solar water heating forum. there is much to learn about materials and techniques

DIY as you choose, just don't expect it to work as well as a system using components designed and sold for the purpose. Do it for the education, not for end product quality or cost effectiveness, and certainly not for aesthetics.

[Mike90250]

line the pool with black plastic and use a cover.

[barnsley]

thanks for the replies. I'm checking out the builditsolar site (bit of a minefield at the mo tho). - is there a solar hose pipe / panel calculator anywhere?

I have a 400 micron soalr cover and another cover for night time. - is it better to leave the outer cover off in daytime even when it's mostly cloudy? (to make the most of the solar cover)? - os just when it's sunny?
I'll also look for some black plastic too - if this makes much of a difference?

[Logan5]

there is a sapphire finish pool brite that is very dark and could work well with a clear cover. but during the summer the pool would get hot.

[J.P.M.]

thanks for the replies. I'm checking out the builditsolar site (bit of a minefield at the mo tho). - is there a solar hose pipe / panel calculator anywhere?

I have a 400 micron soalr cover and another cover for night time. - is it better to leave the outer cover off in daytime even when it's mostly cloudy? (to make the most of the solar cover)? - os just when it's sunny?
I'll also look for some black plastic too - if this makes much of a difference?

Approx. 1/2 of the heat loss from a pool is due to evaporation. If any cover is "wet", the wetness will increase the effectiveness of the cover. A clear bubble cover can mitigate that e evaporative loss somewhat by virtue of its somewhat greater insulating value. In very dry climates, dark, non bubble covers that can double as solar collectors due to their color may be better, depending on nite time conditions, including rel. hum. Any cover will produce the highest pool temps. when left on the water whenever the pool is not occupied.

[barnsley]

there is a sapphire finish pool...but during the summer the pool would get hot.

hot? In the uk?

[barnsley]

... Any cover will produce the highest pool temps. when left on the water whenever the pool is not occupied.

Sounds like I've wasted £70 on solar cover then (cost that for the pool).

[J.P.M.]

Sounds like I've wasted £70 on solar cover then (cost that for the pool).

Not if your using it. What I'm writing is that a pool cover works best when it's on the pool for the max. amount of time. Sort of meant as a no brainer.

[barnsley]

I meant wasted because I already have another cover (a normal non-solar cover) so I don't see point on a super-dooper solar cover if its best to have the other cover on most of the time?
I keep both covers on and use an Athena solar power heater and it feels like same temperature as when I filled it with cold water! (Although its been mostly cloudy) guess its probably cold because it's never had chance to warm up in the first place

[J.P.M.]

I meant wasted because I already have another cover (a normal non-solar cover) so I don't see point on a super-dooper solar cover if its best to have the other cover on most of the time?
I keep both covers on and use an Athena solar power heater and it feels like same temperature as when I filled it with cold water! (Although its been mostly cloudy) guess its probably cold because it's never had chance to warm up in the first place

If you have a cover already and you keep rainwater off it, it will do a pretty fair job of heat retention.

A thing's temperature is a result of heat gain and loss. A mass of water and its container will gain heat from the sun and the surroundings (if the surroundings are warmer than the water) and lose heat when the input from the sun is less than the losses to the surroundings or when the sun is absent. It's called a heat balance. If the rate of heat transfer (mostly loss) is reduced by a cover, the water temp. will increase faster and lose heat slower.

Water has the highest heat capacity,by far, of any common material. A pool has a very large thermal mass compared to an equal volume of, say, rocks. even an equal, solid volume of steel cannot store as much heat per degree of temp. change. What solar energy is available will heat the pool water. It may take a while but it will put energy into the water. Once in the water, it will stay there longer when the cover is in place.

[barnsley]

Well I've got my diy solar kit set up and even when the sun shines it hardly lukewarm inside. I'd be better off putting my 200ft of hose in the shed cos it's warmer in there. 
I can't see any advantage yet of using polycarbonate. But maybe it's because I've not fixed it down yet and there are gaps around the edges. It just seems that the polycarbonate sheet offers more shade than harnessing the sun.
I think I would have been better just putting the hose directly on the shed roof, as when autumn comes I only have to take it out of the frame to extract the water for winter storage.

[barnsley]

Thanks

finally, after some proper sun I can feel warm water coming out of my 200ft (60m) length of black hose pipe.
however, my flow rate is seriously reduced to a trickle.

my pump is 0.5hp and should be 300 gallon (about 12 litres) per hour, but I'd estimate that I'm only getting 1/10 (one tenth) of this when its connected my diy solar heater contraption.

I have it on the ground at the moment, but i want to put it on the shed roof. I did a test and put 100 feet on the roof ) conencted 32mm outlet from filter pump to a 13mm (half inch) hose and got zero water coming out! - it does not have the strength to pump up to my shed which is 7feet high.

Anyone know how much power i need to pump more than a trickle of water up a 13mm hose 7 or 8 feet high please?