Thermomax Evacuated Tube Solar Hot Water

[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.