Deciding if I should build this solar heater

Author	Message
rogerdw Guru Joined: 22/10/2019 Location: Australia Posts: 955	Posted: 11:43am 11 Apr 2021         Solar Mike said   I have made a few DIY heat-pipes and can give you some pointers on how to do it. Wow, never ceases to amaze me the wealth of experience and knowledge on this forum  ...  thanks Mike   Quote   A single 15mm heat-pipe can move over a KW of heat, providing you can cool it fast enough to condense the gas. All this discussion has me wondering whether using heat pipes are a more efficient way of harvesting the heat from the tubes  ...  or just a different way than blowing air through them. Certainly if the aim is to heat water  ...  heat pipes being inserted into a water carrying manifold sounds like the only sensible way of extracting the heat  ... ...  but if the aim is simply to remove the heated air  ...  just blowing or sucking it through should be easy enough. Of course it then depends on what is done with the hot air as to how efficient the heat collecting method would be seen.   Quote   Those heat pipes used in the evac glass tubes are only 6mm thick and have water in them, they have a springy spiral of thin alloy sheet that clamps over the inner tube and press against the black coated glass to get the heat into the pipe. Great description  ...  I'm assuming the thin alloy sheets were pretty much the full length of the evac tube like the ones I have seen? As I said above, trying to replicate 30 of those struck me as being harder than trying to recreate 30 x heat tubes.   Quote   I believe a more simpler and cost effective method is to construct a simple timber case, glazed with clear polycarbonate with a black painted fly screen door type material inside to capture the heat warming the air in the process, its the surface area that's important, not a small volume of high temperature to warm up enough air to feel inside your house. Interesting you should say that Mike  ...  it is the exact same conclusion I had come too  ...  other than the fact I have access to all these tubes for $100. I suppose I will never know unless I build one of each and compare them, not that that is likely to happen  ...   ...  though I came to this conclusion by reading all the reports of someone who did a heap of side by side comparisons and found that collectors built as you described were not only the easiest and cheapest collector to build  ...  but were also the most efficient. I am left wondering though  ...  if a clear topped collector with a couple layers of black flyscreen was so good at collecting heat (hot air)  ...  why aren't they also being used to heat water. There's no question that evacuated tubes can do an amazing job of heating water even in winter  ...  and I really can't see the flyscreen collectors being anywhere near able to compete. I'll put a couple links to examples of the flyscreen collectors. http://www.mckayphotography.com.au/photos/solar-mk3/ http://www.mckayphotography.com.au/photos/solar3/