EcoRenovator - View Single Post - Dump the plumbing and use PV to heat water?

stevehull · 07-20-13, 07:01 AM

My very first solar water heater used black plastic tubing in a drain back configuration - disaster! Here's why.

Built a box with glass and insulation, put in the plastic tubes, etc - all along ideas used at the time (1978). Used a "drain back" configuration so that it was simple and would only turn on if the heater thermostat detected warmth. then circulating pump turned on.

Had a simple heat exchanger (coil of copper) in an insulated tub.

One sunny day the main power went off to the area and after an hour it turned back on. The water went up into the VERY hot collector and immediately flashed into super heated steam. Melted every one of the black plastic heat exchanger tubes.

I rebuilt with type M copper tubes . . . .

Steve

07-20-13, 07:01 AM	#56
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	My very first solar water heater used black plastic tubing in a drain back configuration - disaster! Here's why. Built a box with glass and insulation, put in the plastic tubes, etc - all along ideas used at the time (1978). Used a "drain back" configuration so that it was simple and would only turn on if the heater thermostat detected warmth. then circulating pump turned on. Had a simple heat exchanger (coil of copper) in an insulated tub. One sunny day the main power went off to the area and after an hour it turned back on. The water went up into the VERY hot collector and immediately flashed into super heated steam. Melted every one of the black plastic heat exchanger tubes. I rebuilt with type M copper tubes . . . . Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990