Introduction: Solar Water Heater for Pool
This is the pool that sucks up massive amounts of propane to keep it at the preferred temperature of 80+. Last year I did an experiment with 50 feet of 1/2 inch black polypipe coiled on a board to test the solar hearing theory. The test was successful so here is my integrated solar heater instructable.
Relatively inexpensive. The most expensive pieces are the 2" ABS sections and the PVC pool fittings. All in I spent about $100. $50 in fittings and $50 in other bits and pieces.
Chop saw, drill, drill bits, glues and a custom made thread cutter for the ABS.
Step 1: Select Your Point of Entry
The 1st thing to figure out is where you will cut into your pool system to install your heater. Most pools have 1 main return to the pool, so you will need to cut that open to create your solar system access. My pool happens to have a splash pad with 3 independent feeds all with separately controlled flow valves. I cut into the centre water feed that just happens to run into my pool house on the end. As you can see from the pic it is just a normal 2" PVC pipe. I cut out about 3 feet of pipe to create my bypass.
You will need the following parts for this section of the build.
2 x 2" PVC flow control valve
1 x 2" PVC coupling
2 x 2" PVC T junction
2 x 2" PVC 90 degree elbow
Section of 2" ABS pipe
Plan out the pieces and test the fittings for size before glueing them together.
In my example the main flow valve is open and the solar flow valve is closed. The solar system would not be running. By opening the solar flow valve leading to the solar system you allow water to start circulating into the solar system. Close the main flow valve to force all the water into the solar system. For those of you that only have 1 pipe going to your pool you may want to have some water still flowing directly. Keep in mind of too much water is put through the solar system it flows so fast that there is very little time to pick up heat. A steady slow to medium flow is best for the solar system.
Step 2: Bring Your Pipes to the Roof
In this step you will extend the pipes to the roof. You will use 2" ABS pipe now, as it is less expensive and it is black to attract the sun and heat.
Use transition cement to connect the ABS to the PVC elbows extending them up to approximately 4-6" below the roof line. Add 90 degree elbows and run the pipes to approximately 4-6" past the roof edge. In my pics I run the pipes to the side of the roof as there is an eavestrough on the lower roof edge. Add more elbows and straight pieces until your pipes are on the roof ready for the solar heater system.
Step 3: Build the Solar Assembly
This part can be scaled up or down to suit your needs. You can use anywhere from 8 to 16 pieces of 1/2 inch polypipe to create the heating assembly. Minimum of 8 pieces to allow for the flow of the water going from 2 " to 1/2 " pipes. The import thing to remember when designing the system is to have the water flow UP the roof. If you try to go sideways along the roof then the bottom lines will fill and the upper ones will not have water flowing through them do to gravity and pressure. By having them flow up that will all fill equally and flow at the same rate to the top of the system. They then dump into a 2" collection pipe and are carried back down to the pool system.
10 x sections of 1/2 inch poly pipe
20 x threaded barb connection for 1/2 inch poly pipe
20 x hose clamps (small)
2 x 6 foot sections of 2 inch ABS pipe
2 x 2 inch ABS caps
In my example I used 10 pieces of poly pipe, each piece is 10 feet long. They are spaced out about 8 inches between each pipe. To create the connection between the 1/2 inch poly and the 2" ABS I did a bit of a McGiver job. I drilled into the ABS every 6 inches using a 3/4 inch bit. I then created a thread by using a home made pipe thread cutter. Buy a 3/4 inch threaded black iron fitting and take a grinder to it to cut grooves into the fitting. The edges of the grooves will easily cut a thread into your holes. As it turns out the threaded barb connections for 1/2 inch poly pipe have the same thread as the black iron fitting.
Once you have tapped and threaded all the holes wrap the poly connection in teflon tape add a few drops of gorilla glue and thread it into the 2 inch pipe. Be very careful as there is not are not a lot of threads holding this in place. Enough to make it work but no extra. I also used PL construction adhesive on the connections for added strength and to make a firmer seal.
To join the poly lines to the barbs drop 2 hose clamps onto the line then heat the end gently with a low flame propane torch. Just enough to make it soft. This will allow you to insert the pipe onto the barb without too much pressure. Once you have all the lines attached time to bring it to the roof.
Connect the rest of your pipes, tighten all hose clamps and screw the polypipe down with clamps and steel roof screws. I also used aluminum hanger to secure the main feeds to the roof. There is a 1 to 2 degree (C) 2 to 4 (F) difference between the feeds to and from the roof. Enough to make a difference. Brought my pool from 75 to 80 in the 1st weekend.