Excellent and unique product. I installed it to heat my hotub at my summer cabin. OFF GRID!!! Shipping was fast. Great customer service with Mark in Tech support.

Company is fantastic to deal with and I look forward to reordering. Great warranty.

Not a magic solution..but neat. Filled tubes with DRY sand to increase efficiency. It will generate a good amount of hot water. Would be PERFECT for an off grid hunting cabin or a small pool heater. I drilled a hole the size of the 1/4″ copper tubing into the screw cap on the intex pump. The intex filter pump draws cold water from the pool hose outlet through heater back to the pump/filter and back to the pool. This will only add maybe 1/3 deg per day…but that is 10 deg in a month. I could see using 3+ of these or a larger system to heat a pool with sunlight.

Excellently simple and effective technology. I had never heard of these, but they’re a great simple fix to the solar energy capturing problem. Just some glass tubes and a protected black metal coating. These are going to be more efficient in cool climates than a simpler solar box with painted-black PVC inside… Anway, I just got my box of these. Going to order again. On the website it shows some DIY projects on how to hook these up easy-peasy. Filled one with water, and standing out in the sun (thin clouds partially obscuring the sun) – after 10 minutes the water is 20 degrees hotter than the adjacent stucco wall (upon which the sun is also shining) – so they do work very well even in partial sun. Basically, if the tubes cast a shadow, that’s enough sun to capture more warmth than anything else nearby does. Double efficiency if a simple aluminum foil reflector is used to illuminate the back of the tubes… Attached pix show tube and level of cloudiness during my test. Water after two hours is 134F but pavement beside water is 90F. Also, tube outside is cold to the touch.

Great tubes boils water 15 min if you build collector, BATCH WATER HEATER IDEA! I got these and took them out to see if they would work and they do, I had 20 oz of water roaring boil in under an hour. If you are in a smokeless camp this is huge especially if you want to avoid detection in a stealth camping mode. I came up with an idea that I have yet to try. What you do is take a tote then use a mylar blanket (Emergency blanket) you line the tote with the blanket then you add your water. If done right the water should heat rather rapidly this would be a batch water heater for something like 5 gallons. See first I tried to silidone the tube to the outside of a 5 gallon bucket that did not work so well just leaked no support for the tube and hardly transportable. Gave up I need to be able to transport. This idea I have now would allow you to pack your tubes in the safe case they came in and you can set the tubes in the water have the tube just do its thing and it should heat the water this way it might have stratification issues but I think in 2 hours 5 gallons should be so hot you might have to change to a metal pan. IDK I have not need for it right now so it is not much a priority to do this. If you were camping and water was a valuable commodity IE as expensive as fuel because you used fuel to go get it? Then you would want to make your water count and washing clothes hot water is the best. I would build a filter out of some PVC,ACTIVATED CHARCOAL (fish section $6 WMT) and some Sand.