Thursday, October 18, 2018


15 Responses to “solar water heating”
  1. solution246 says:

    @sundug69 I got it. Thanks so much.

  2. sundug69 says:

    @solution246 Lots of places, but for some reason I cannot post links here, just do a search

  3. solution246 says:

    Where can one get an evacuated tube?

  4. sundug69 says:

    I have no way of knowing

  5. adxoplo says:

    How many BTU’s per panel? Thanks, great vid.

  6. sundug69 says:

    @12robot345 I did not evacuate the copper tube, I just heated the acetone some to drive the air out, nit the same thing at all. I know about the vacuum in the evacuated tubes. And the size of the copper tube doesn’t matter, as the insulation value of the vacuum is so good that all the heat (not solar at this point) goes into the smaller tube as I have the copper scrub pads as conductors. This enables using less costly copper, and is the way they are made commercially. Forget fluid thru the tubes

  7. 12robot345 says:

    Okay, quick Engineering tip: Evacuating the inner copper tube is really a waste of time. The vacuum you’re interested in is the vacuum between the glass tube and the copper tube. you want that so you don’t lose the solar heat back out to the environment through conduction. A better plan: bigger copper tubes painted black. More surface area to absorb solar radiation. Pass fluid through tubes. Use anti-freeze so it doesn’t freeze, and so the pipes don’t corrode. Good luck!

  8. 1foxtrot70 says:

    LOL, that sounds like one of those exciting moments of science thru experimentation.

  9. sundug69 says:

    Trial and error, and the error can get dangerous. Instead of rupturing the tube, the bulb blew off and went completely over my house!

  10. 1foxtrot70 says:

    How did you decide on 8 cc’s of Acetone? I am sure this is one of those things where more is NOT better. I can see where an optimum amount, if exceded, would rupture the tube.

  11. matrixm777 says:

    Nice video….

  12. toadabc says:


  13. sundug69 says:

    I used copper anti seize paste to improve the thermal transfer from bulb to fitting.

  14. sundug69 says:

    My other videos show that the bulb slides into a coupler fitting, which is soldered to the manifold pipes. The bulb is not soldered to the coupler.

  15. toadabc says:

    I appreciate the specific information. I understood the heat tube you make, and how it goes into the vac tube, but I didn’t see how you attached your heat tube to the manifold, where it “gives up its heat”. Thanks for the vid.

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