[Mike]

Hi All,

Yes, we are now selling the Clean Republic solar vacuum tubes at:

http://cleanrepublic.com/box_of_solar_vacuum_tubes.html




They are a ton of fun and great for DIY research and home solar heating projects. No more hunting around all the foreign web sites trying to find a supplier you can work with. You now have a U.S. source for solar vacuum tubes!

Cheers,

Mike

[Mike]

Hi Guys,

We've just received our new inventory of 700 tubes for R&D and home project work (as well as in our mad science lab here). They went really fast last time. We'll order more, but we may have another few months where we're out of them, so get them while they're hot!

http://www.electric-bike-kit.com/solar-tubes.aspx

Cheers,

Mike

[PhredG]

How might these solar vacuum tubes be integrated into some kind of circulatory system? Is there a way to build them into a manifold frame of some sort? Based on the pictures it appears the tube is open on one end and closed on the other end with no way to link them serially or to rack them in a framework. What other operating specs are available? For example, are they rated to a specific temperature or pressure? Do they have a calculated lifespan? Any other more detailed info about these tubes is appreciated. TIA.

[Mike]

Hey TIA,

Good questions. We just sell the tubes right now because they are the 'magic' part of any solar water heater system and people have so many different ideas about what kind of manifold or flow system they want to build. All those other parts can be built out of simple stuff from the hardware store, though, so we sell the exotic component (the tubes) and let our customers do whatever else they want.

We are working with our customers in brainstorming more detailed systems that we can sell components for in the future. We're doing our own testing and inventing with the tubes here, and we'd love your help with pictures or ideas from any work you do with them. We can share your projects, pictures and ideas on the forum to help everyone experiment with their solar projects too, if you like.

The tubes should last a long time in terms of performance, say 10 years at least. Without water directly inside they can reach temperatures over 300'F. They are NOT build to hold any pressure, so don't seal off the open end or let pressure build up inside in any way.

There are lots of possibilities to work with them including running pipes or hoses in, down, up and back out of them, filling them with water directly, and many other options.

Looking forward to sharing the development with you!

Cheers,

Mike

By the way, here's a vid showing the inside layers of the tubes:

[PhredG]

OK, thanks. Based upon your response it sounds as if each tube is factory sealed on one end so that any heat exchange fluid needs to be piped in, down, around, back up and out in order to withdraw collected heat. Is that correct? I was kinda hoping they could handle pass-through exchange. Back to the drawing boards. It doesn't sound like there is any solar or thermal efficiency data for these products yet?

[Mike]

Hi Phred,

That's right. We're looking into the possibility of having them made with two open ends. As it is now, you are correct, one end is sealed as a result of the standard manufacturing process. The same process that caps one end has a lot to do with how they can be made so affordable. So, I'm sure it's technically possible to make them with two open ends, but it's not necessary for their original intended purposes in roof-top arrays, so the manufacturers don't do it. It's possible in the future we could get some done for us with two open ends, however, since many people are asking for that.

For the foreseeable future they'll be closed at one end, so yeah, better to build designs based on that for now. Check out the video I just added to one of the above posts. It shows some more detail of that closed end.

Cheers,

Mike

[PhredG]

Thanks. The video is very helpful as it shows the actual design of the tube. And yeah, this configuration will be much cheaper to fabricate and probably works better for garage hobbyist demo's. They do seem like pretty cool tubes. Or hot Very demonstrative. But I'm still trying to imagine how to optimize the heat transfer for productive use (and/or work) while the open end always needs vapor outlet and fluid replenish. I gotta believe somebody has captured some performance and efficiency data but oh well. Thanks. Very cool.

[techmaster]

Has anyone come up with a manifold system yet? I am trying to come up with an innovative way to heat my pool. It looks to me like a cap with an in and out tube could be added to the top with a dip tube similar to a water heater on the in. The in could go to the bottom and if you put them in series you could loop from one to the next. Would the chlorinated water shorten the life of the tubes? My thought was the water would have to move thru the tubes very slowly for proper exchange. How strong is the glass? Would it have to be protected from the elements if they were installed on a roof? Looks very interesting. Thanks for the feedback.

[Mike]

Hi Guys,

We're trying a bunch of different options for very simple, affordable ways to circulate the water. Here's one:

This design stresses the glass a little too much for my comfort, with the weight of the water inside, but could work. It could also be less stress if the PVC component used 45-degree side connections instead of 90-degree.

They are tough enough to survive outside on a roof in the rain, wind, and even light hail, but 1" hail or tree branches hitting them would probably cause a little damage.

We'll keep adding ideas as we work on easy ways to circulate the water without the $10k systems you find elsewhere. Please post your own pictures and videos here also to help share and brainstorm.

Cheers,

Mike

[techmaster]

Mike,
Thanks for the response! My thoughts are to create a protected bed if you will for them to lay in. The pitch on the roof is 4/12 so I already have the slope for natural convection. Obviously I would need to pump the water up there. Any thoughts of how much water I should move? Would it be better to series the tubes or parallel them? The water would have to move very slow if paralled in my opinion. If they were seriesed lets say with 10 tubes could it move faster and have the oppurtunity to be heated 10 times? Is this logical? I need to come up with an in and an out cap for each tube, I think. I will be thinking about this some more but if anyone has thoughts it would be great to hear them.

[Mike]

Hey Tech,

Here's a video of another concept I'm experimenting with, that could be really great in certain situations, for certain purposes:



I much prefer designs with natural convection, like you are proposing, because of the simplicity and the fact that there aren't any moving parts to break down, however simple they may be.

Yes, any incline will induce convective flow naturally, and I agree with your theory of "connecting in series." In theory, if you can get water to actually flow in and out of the tubes naturally, without 'passing some tubes by' then the water would get hotter and hotter as it flowed on through each tube. This would be a good design for some system that you needed to heat a small amount of water as fast as possible, with 10 tubes you could heat a few liters to boiling in maybe an our and a half of direct sunlight.

However, if you're trying to heat up a large space, or regulate temperature somewhere with a big tank of water, just getting the sun's energy into the water is the big deal, more so that exactly how hot it gets, and you might not want a large volume of water to be anywhere near the boiling temperature anyway, depending on where it is and what it's held in. So there could be many times when a "parallel" flow system would be best.

We're also working on some systems that don't flow the water anywhere at all, and just have water/tube "modules" that fit in window frames so they soak up sun during the day, let some light through, greatly improve the insulating quality of the window itself because of the thickness of the tubes, and then also slowly radiate the heat from their hot water back out into the room during the evening hours after sunset. I think this could be a really great way to go because it could be a total end-run around all the flow/transfer related issues altogether. However, there are lots of specific projects where have a a big circulating system is just what you need.

Grab a box of tubes and send in some pictures of what you're working on. We'd love to see what you're coming up with!

Cheers,

Mike

[techmaster]

Hey Mike, thanks for the video as it is what I was thinking. I already have the pump available for the pool and I can regulate the flow thru a valve which is already also there. Can a pvc cap be glued to the top? Would 100% silicone be enough to hold the cap? Since I would be pumping the water, do you think it would be good to have the intube to go to the bottom of the tube? If I used a 1/4" tube I don't think I would reduce efficiency too much since I am taking up space in the tube????? I would also like to order 1 tube to look at it and experiment with it.

[Chris Clean Republic]

Hey everyone!

The Solar Vacuum tubes are now back in stock! You can use these to heat water with the power of the Sun. Check out the product page here: http://www.electric-bike-kit.com/solar-tubes.aspx. Get them before we run out again!

[Mike]

Hey Guys,

Here's a quick snapshot of a new technique we're working with that's very easy for you to use in your own shop.

Please send in more videos and pictures of how you are using the tubes to heat things with solar power!



Cheers,

Mike

[Conor5]

Does anybody have any experience of Firebird Sydney solar tube systems?

Apparently they are made in Ireland. My plumber has recommended them over the Kingspan Thermomax. He said they perform better and are cheaper.

They are made in Ireland and SEAI registered

[Chris Clean Republic]

Conor5,

Good question. I honestly don't have experience with those systems. Anyone else?