Thermomax Evacuated Tube Solar Hot Water

[jimad]

It may not be obvious, at least it wasn't to me, but solar hot water heaters don't work by absorbing "heat" from the sun.  Rather, they work by absorbing solar radiation from the sun.  Thermomax evacuated tube collectors use this by absorbing the solar radiation onto a surface inside a vacuum tube, where even in cloudy condition things heat up enough to boil a special liquid inside a heat pipe contained within which then transfers that heat energy to a tab on one end of the collector that heats up your hot water flowing by in a plumbing pipe.  Point being Thermomax can make very hot water even on cold cloudy winter days, its just that they make less of that very hot water!  I have heard varying stories about how well the tubes hold up in major snow events, not that any of those are left anymore!

http://www.thermomax.com/

[aviken]

I was surprised recently to learn about evacuated tubes and how they work. It is really amazing. This is currently very popular in Europe, and becoming more popular here all the time.

[StorminN]

The evacuated tubes are very popular in Japan and China, as well. The Chinese-made tubes are getting better and better, check out the Apricus brand. I believe the Thermomax tubes are still made in Ireland. The local distributor for them is in Victoria, BC...

Thermomax distributor

-Norm.

[Net Zero Impact]

Hey Everyone,

I just thought I would let you know about the big difference between Apricus, Viessmann and Thermomax. I work for a company that distributes the Thermomax product in the Northwest (Seattle based) so my opinion is obviously a little biased but here are the facts:

Apricus makes an evacuated tube similar to the Thermomax and Viessmann but a big difference is how they seal the tube and maintain the vacuum inside. Apricus basically seals the tube with a glass to metal seal using a large metal disk. This will have increased thermal losses over a short time period. Yes, they put a 10-year warranty on their products but you would be lucky if the product held its vacuum for that long.

Another big difference is the type of glass that is used to make the tubes. Apricus uses a borosilicate glass and Thermomax uses a soda lime glass. Do some research. You will find that soda lime glass is a much better product. If for nothing else, your research will show that the process to make borosilicate glass creates a number of different pollutants. Is anyone proud of the environmental efforts of the Chinese? Doesn't it seem like a solar manufacturer should be taking every step possible to maintain a clean environment?

Thermomax and Viessmann have the exact same solar evacuated tube. They are both created to the same specifications. The biggest difference between these two brands is that Viessmann costs almost twice as much.

Thermomax tubes are guaranteed for 20-years, 10 years more than any other evacuated tube including Viessmann and Apricus. The difference is quality, quality, quality. There are Thermomax tubes out there right now that are still operational...from 30 years ago!

Last and certainly not least, Thermomax is the safest tube on the market. They have a patented self limiting device that if for any reason the tubes were to heat up above 275 degrees F they would shut themselves off from the manifold and prevent scalding of the liquid and system. No other company offers this on their tubes, including Apricus.

If you are interested in learning more then check out the website:

www.kingspansolar.com

www.netzeroimpact.com

[CarbonSmart]

I saw this and I just had to say a couple of things,

First I have a bias already as an Apricus distributor/wholesaler. However claiming that the tubes are more susceptible to losing their vacuum is totaly bogus for a couple of reasons. As a side note Apricus has a very different tube design than ThermoMax and Viessmann

First, the "weld" Net Zero mentions is simply the bottom of the tube where the glass has been fused after being evacuated, I dont see how fused glass is going to breakdown over time. And saying it will be lucky to last ten years is unjustified, considering thermomax/kingspan was forced to recall a large number of its own tubes in the last year after many failed in the field, correction; extremely unjustified.

Second, having an all glass seal means that you are only dealing with one thermal expansion rate. As these tubes heat up and cool down they expand and contract, this is the greatest risk for losing vacuum prematurely. All glass seals have no chance of weakening over time due to this effect while metal on glass seals i.e. Thermomax,Viessmann and any other single wall evacuated tube are more susceptible because the seal is made by fusing metal around the glass to maintain vacuum. While obviously the high quality single wall tubes such as Thermomax and Viessmann try to match metal and glass components with the closest possible thermal expansion rates, they still are not identical and will lose their vacuum due to thermal stress far before a tube with an all glass seal ever will.

That being said all tubes will lose their vacuum over time, after 10 -15 years all tubes will see lowered efficiencies due to slow but steady degredation of the vacuum 10-30%. All glass is permeable to gas to some degree and it is inevitable.


On a final note, in the last two and a half years I have only had to provide 7 replacement tubes 4 due to breakage and 3 due to a strange condensate occuring in the tubes (all three in the same collector). All were covered under warranty. I'll stand behind a product with that track record in the field.