New to solar... kinda

[dougget]

Hi,
A good friend of the family was into solar back in the 80's. Passive solar heat in his house and did some residential installs too. I did an 8th grade presentation on solar heat in one of my classes too. The good ol days.
Now I have a domestic need for some solar heat and am interested in building a solar panel to heat my pool.

I'm interested in reuse/recycle when possible, but want my pool heater to look good, not all pieced together from 'found' materials.

So... the plan is to use about 500' of 1/2 inch irrigation tubing. This is the kind of plastic tube that would be used to carry water from a timer valve to various watering sprayers around a landscape set up. The material spec says UV resistant. I don't think anything is UV proof, so that's about as good as it could get.

First thinking about a standard 4x8 sheet of plywood... but I really want to cover it with glass. A 4x8 sheet of glass is not cheap, so I'm thinking about reusing a pair of sliding glass doors. I see some advertised on Craigslist for $30-$50. With those side by side, my panel will be about 60" x 80" slightly larger in total square inches than a sheet of plywood, but still plan to use about 500' of tubing.

I've seen various pictures on line and the construction seems fairly simple. Plywood panel with a 2x4 trim around the perimeter. Coil the tube flat on the plywood. Paint everything black. Cover with glass.

But I have a couple of questions:

The coil pattern: I saw one example where the tube started to coil in to the center from outside, then in the center of the coil, the builder put in two 90deg fittings to make the tube do a U turn and coil back out. So if you looked at the coil each ring would alternate between inbound and outbound water. Not sure if there is any benefit to that other than keeping the coil flat against the plywood vs having the tube come from the center of the coil over the coil to the panel output... Opinions?

How to pump water through the panel: I do not want to add another pump to the set up. I do want to use the filter pump that is already running to filter the pool water. BUT the diameter of the tube in the solar panel will be significantly smaller than the filter hoses so I do not want to pump 100% of the water through the panel. Will a "T" fitting on the return line to the pool have enough back pressure to push water through the panel?

Some additional info: Above ground 24' pool. 1.5 HP pump. Panel would be mounted at an angle with the bottom edge slightly above the ground. Distance from the pool would be less than 20 feet. The top of the panel may be slightly above the water level in the pool.

I'm very excited to put the sun to work at my house. Thanks in advance for the support from this forum.

Doug

[ILFE]

Take a look at THIS LINK. It should help address most of your concerns, even ones you haven't thought of yet.

[J.P.M.]

Hi,
A good friend of the family was into solar back in the 80's. Passive solar heat in his house and did some residential installs too. I did an 8th grade presentation on solar heat in one of my classes too. The good ol days.
Now I have a domestic need for some solar heat and am interested in building a solar panel to heat my pool.

I'm interested in reuse/recycle when possible, but want my pool heater to look good, not all pieced together from 'found' materials.

So... the plan is to use about 500' of 1/2 inch irrigation tubing. This is the kind of plastic tube that would be used to carry water from a timer valve to various watering sprayers around a landscape set up. The material spec says UV resistant. I don't think anything is UV proof, so that's about as good as it could get.

First thinking about a standard 4x8 sheet of plywood... but I really want to cover it with glass. A 4x8 sheet of glass is not cheap, so I'm thinking about reusing a pair of sliding glass doors. I see some advertised on Craigslist for $30-$50. With those side by side, my panel will be about 60" x 80" slightly larger in total square inches than a sheet of plywood, but still plan to use about 500' of tubing.

I've seen various pictures on line and the construction seems fairly simple. Plywood panel with a 2x4 trim around the perimeter. Coil the tube flat on the plywood. Paint everything black. Cover with glass.

But I have a couple of questions:

The coil pattern: I saw one example where the tube started to coil in to the center from outside, then in the center of the coil, the builder put in two 90deg fittings to make the tube do a U turn and coil back out. So if you looked at the coil each ring would alternate between inbound and outbound water. Not sure if there is any benefit to that other than keeping the coil flat against the plywood vs having the tube come from the center of the coil over the coil to the panel output... Opinions?

How to pump water through the panel: I do not want to add another pump to the set up. I do want to use the filter pump that is already running to filter the pool water. BUT the diameter of the tube in the solar panel will be significantly smaller than the filter hoses so I do not want to pump 100% of the water through the panel. Will a "T" fitting on the return line to the pool have enough back pressure to push water through the panel?

Some additional info: Above ground 24' pool. 1.5 HP pump. Panel would be mounted at an angle with the bottom edge slightly above the ground. Distance from the pool would be less than 20 feet. The top of the panel may be slightly above the water level in the pool.

I'm very excited to put the sun to work at my house. Thanks in advance for the support from this forum.

Doug

Doug: Now See This: Builditsolar.com. Lots of ideas for DIYers.

Keep in mind that for serious pool heating, depending on a poolful of variables, you'll need something like ~~ half to 3/4 of the area of the pool as an effective heater size. So 800 ft.^2 of pool will need something like 400-600 ft^2 of pool heater. The sun can be a cheap fuel source, but one of it's drawbacks is that it's not real concentrated. You need a lot of real estate for solar to do the same thing as a gas fired heater, and do it with less resource reliability. The world is full of tradeoffs.

Been there. Had a lot of fun. Enjoy yourself.

[skeeter_ca]

Both those links given are great for getting building ideas. Forget the glass cover, you don't need it. Build four (you will need at least four to make any kind of useable heat) 4'x4' squares with plywood and add some small strips of wood on the edges to help the plywood be rigid and hold in the edges on the pipe. Paint black. Coil about 180'-200' of poly pipe on each plywood sheet using a cross brace to hold down the pipe. Connect these to your pool pump return line in parallel with a valve to bypass some water if you want. Use the same or larger size header pipe going to and from the solar panels that the pump uses. Make the solar return to the pool water inlet. WALA!!! Solar heater.

skeeter