Self Freeze Protected Direct Thermosiphon Solar Hot Water Heater
This two minute video shows a thermosiphoning solar water heater in Denver, CO. It uses a very low loss coefficient SunMaxx VHP-20 solar collector which lose…
3 Responses to Self Freeze Protected Direct Thermosiphon Solar Hot Water Heater
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This Thermosyphon heater must return the warmer water at a higher spot in the tank than it received the supply water. Otherwise effective reverse thermosyphoning won’t occur when the collector gets cold.
Imagine if the collector supply and return were both at the bottom of the tank. It would heat up OK, but when things get cold, the coldest water would just remain pooled in the collector, and it would eventually freeze.
I’m also using
Kevin Dickson
June 29, 2013 at 4:29 pm
Why is the return hot from the collector running to the top of the tank? wouldn’t you want it connected to the bottom to allow the hot water to rise in the tank?
bipth
June 29, 2013 at 4:49 pm
We were able to get it to freeze during zero degrees, but ONLY by covering the collector with a tarp, and ensuring the tank was completely full of fresh cold city water.
The thermosiphon effect essentially stops at 39F (when rho dot changes sign). Therefore this design should be restricted to climates where the incoming city or well water never drops below 45-50F.
We’re on to something here:
1. No antifreeze
2. No heat exchanger
3. No pump, sensors, or controller
4. Std. tank
Kevin Dickson
June 29, 2013 at 5:44 pm