I installed my own evacuated tube solar hot water heater system. It was and still is a learning experience. One thing I learned is that you must take serious precautions against collector overheating. An overheated collector can leave you with evacuated tubes that are no longer running at 100% efficiency.

Now when I do maintenance on the system that involves opening the circulation loop, I place a reflective tarp over the collector before I shut down the circulation loop. Without water running through the collector’s manifold, the evacuated tubes get extremely hot, and while manufacturers claim it does not hurt them I beg to differ. After allowing my tubes to overheat twice, I can tell you some have experienced a decrease in efficiency as evidenced by the feel of the tubes. Even though the vacuum appears to be intact, some tubes are warm to the touch and that means the vacuum has been compromised at least somewhat. I still get plenty hot water on sunny days, I know if I replaced the half dozen or so tubes with warm surfaces, my water would be much hotter at the end of the day.

Being able to conveniently get to your collector to cover it up, is why I regularly argue that putting the tubes on a platform on your property makes a lot of sense. Who wants to crawl up on the roof and take a chance of screwing up your roof to place a cover on the collector. Some of my good friends will design an automated cover that will rotate up over the collector when the temperature gets too hot, thereby eliminating the need to crawl up on the roof to cover the collector. I hope the friend will let nuSun manufacture the apparatus for sales to all those who need this fix.

This entry was posted on Friday, September 4th, 2009 at 1:03 pm and is filed under Solar Water Heaters, Evacuated Tubes. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.