You all probably know by now that the weather here has not been the best in recent memory. It has been, relatively speaking, very cold so far this year. Our swimming pool temps have been in the high 60's & low 70's. That's a bit cool for causal swimming and frolic-ing. We had a contractor quote a heating system for our pool water but his quote was off the map. $$$$$$$ Also the cost to run this system would be astronomical in Cancun. So my friend Karl (whom has done most of this work) and I came up with the idea to try and build a “solar heating” system that would be almost free to run. It only requires enough electricity to run a small pump to circulate the water. (1/2 HP 110v) We started building it this past Monday and today we got it operational. It works mechanically, and now we have to refine it, to make it work well enough to raise the temperature of the pool water from 72-74 to close to 80. The system is basically simple. You pump water from the pool with a pump up to some coils of tubing that are mounted on a black surface that is in the sun all day thereby absorbing the heat in the coils into the water and then back to the pool where the now hot water is added to the cooler pool water. I have a casita/pool house that is in the sun most of the entire day, so its roof was put into service as the place to mount the heating coils. I painted two 4x8 sheets of plywood flat black for maximum heat absorbsion. Then we mounted 3/4" dia. black plastic flexible tubing to it in a continuous coil. We only built up one of the proposed two panels to make sure the concept works mechanically. We still have to tilt the coils approx. 30 deg. to better face the sun. We borrowed the pump from our tenacca cistern system and ran PVC piping to the pool to provide a suction line from the pool to the pump. Then we constructed another PVC line from the pump up to the rooftop and joined it to the coils of plastic tubing at its lowest point. The water circulates through the tubing absorbing the heat along it's way through the serpentine coils of tubing. Then the water is taken from the high point of the system back down and into the pool. So far we have measured only about a 3F rise in temp, but we know that we have sized the pump correctly and that the system is workable. Now we plan to build the second set of coils and add it to the system, which should allow it to gain more heat transfer into the circulating water. We have a check valve to prevent water from backing into the pool to prevent the pump from losing prime. After the pump we put in a ball valve to alter the flow up to the roof. This way we can have some adjustment to control the temperature. If we can get this to work it will greatly extend the usability of the pool in cooler weather and be very cheap to run. Stay tuned for the outcome.