Pool heating system

This is the third year we’ve had our pool, and it has been really great, but it’s always been a bit chilly.  Last year, we bought solar sun rings, which helped a lot, but the water was still too cool.

Poking around, I found a solution from Gull Industries that used flat coils of black tubing:

Here’s their cross-sectional diagram:

I figured I could build the same thing.  I used the ends of a large wire spool as the hub, and pairs of 2”x2”s as the support spokes:

The separation of the pairs of 2”x2”s is most clear at the bottom of this image:

I then purchased a 400 foot spool of 3/4” irrigation tubing, which has an outer diameter of 9/10”, and wound it around the hub and between the pairs of spokes:

When completed, the diameter of the units is about 6 feet.  I built two of them and mounted them to a south-facing roof near the pool.  The pool has two drain holes at either end of the pool.  I attached drain plug connectors to the drain holes and used them as the input and output for the system.  A pump sucks the water out of the drain hole, pushes the water through the two heating coils, and back into the other drain hole.

It works very well!  The pool has been very comfortable for the summer so far!

I don’t think it ever made it to the blog, so here goes:  two summers ago I built a crude endless pool style swimming machine.  Looking through patents, it appeared that the key to producing a uniform flow is to use a current straightener, which is a structure that forces the water into parallel streams.  See part 24 below:

I built my current straightener using square PVC ballusters, cut into 6” sections and glued together side by side to create a 16” x 8” honeycomb that is 6” deep.  Behind this I placed a pair of low power trolling motors.  Total cost was about $200, compared to $2500 or so for a commercial swimming machine.

The machine worked well, but I think I would need a third trolling motor to hold me back when swimming at full force.  Here’s a video: