Results and video of my first DIY Solar Hot Water Project using 300' coil of Pex
YOUTUBE VIDEO : http://www.youtube.com/watch?v=YBqsrpBSua0
The project consisted of building a Solar Box/Oven for 300' of 3/4" Pex-B Tubing to sit inside of and was built using 2x12's with a finished size of 36"x36" . 1/2" plywood was used for the backing with 1" Polyiso Board sitting on top of that with a thick piece of sheetmetal plate on top of that --- everything inside the Box was painted a flat black including the aborber plate, inner / outer box walls , and Krylon Fusion Paint for the Pex Coil . The top of the Box recieved a double pane argon-filled Low E window in vinyl sash which has good light transmittance with ability to retain heat in the Box. Collector Box is on a 30 degree angle from vertical. Piped in parallel to the water heater so the house hot water supply is either fed by 100% Collector water or from the standby electric Water Heater (accomplished via bypass valves) .
Results after 5 hours of recharging :
90 f. totally sunny day :
Temp. inside Box : 161 f.
Exiting water Temp : 158 f.
84 f. totally cloudy day with mostly rain :
Temp. inside Box : 105 f.
Exiting water Temp : 100 f.
(The Pex Coil holds about 6 gallons, but since i live alone ... it is more than enough hot water for my limited water useage for 100 f. showers and occasional Dishwasher ; in fact on a sunny day I have to cool it down alot with cold water at the Shower Head so Im using less than the 6 gallons of Collector Water. I have the Collector Water bypassing the Water Heater (piped in parallel) and going directly into the hot water line to the house . The Pex I used has a rating of 200 f. at 100 psi and the CPVC leading from the Collector Box to the house is rated at 180 f. at 100 psi. Total material cost : $400)