Old Ireland, new technology. The search for reliable solar water heating.

Around nine or ten years ago I got a Thermomax water heating system installed.  In theory these should provide the home it is fitted to with loads of virtually free hot water, and since the only moving part in the whole system is a pump of the same type fitted to an ordinary boiler, they should be reliable.  It was not cheap, but at that time the tubes came with a 20 year warranty, so I thought at least my investment was pretty safe.  Some chance!  Thermomax went bankrupt, and were taken over by Kingspan, who naturally would not stand by the guarantees made by the old version of the company.

After leaving university many, many years ago, I briefly worked at the Thermomax factory when they were still based in my home town of Bangor.  At that time each tube was an independent unit, using a refrigerant gas to pass heat into a manifold that was connected to the hot water tank.  The factory used to test the tubes by attaching them to clips on the outside wall of the factory, without a manifold.  Since there was then no where for all the heat they generated to go, they achieved some massively high temperatures without major failures.  The problem with them was the refrigerant, since such chemicals are not environmentally friendly.  It is this type of chemical that was largely responsible for the hole in our ozone layer.  For an environmentally friendly company this was a big problem, so the factory was even back then looking for alternatives.  The tubes fitted to our home used no refrigerants, but rather circulated a mixture of water and antifreeze through the whole system, including each of the twenty tubes we had fitted.  Unfortunately this requires a lot of seals to keep the water in the system.  This type of solar water heating requires sunshine, or at least light to work.

The system was unlikely ever to have paid for itself because the panels were extremely prone to leaks, leading to regular visits from the supplier, the labour part of which I had to pay.  This alone would have amounted to far more than the cost savings that the panels ever produced, so when the manifold eventually developed a large leak that would have required its replacement (some of the tubes were damaged as a result of this leak too), I ended up simply switching it off.  It has been a pure roof decoration for two or three years now.  There is no way that I would ever replace this system with something similar; they are simply far too unreliable and far too expensive, especially when that unreliability is taken into account.  This is a pity, because when it did work, it produced a lot of very hot water, and of course it was produced by a local Irish company..

I have recently been looking at alternatives, and other than the tube type solar heating that I have/ had, there is now also a different type that works off air source heating   Of this newer type, I found 3 different systems available.  A local fitter uses the Portuguese made Energie systems, but a quick internet search shows that these may be as unreliable and poorly supported as my original Thermomax system.  Another company making this type of solar thermal is Magic Box, but yet another supplier hinted that these too are far from reliable.  Needless to say, he was pushing his own  (Bunsen) system.  To make any of these heating systems pay for themselves in a reasonable timeframe they need to be both ultra reliable and efficient.  In half decent weather, the COP (coefficient of performance) for them seems good, but no where near the efficiency touted by the sales reps (in fact they unanimously say that COP figures mean nothing but cannot replace it with any meaningful measure of their systems performance.  In cold weather, it seems that it would be more cost effective to run an immersion heater!  That last finding is pretty damning.  Still, all the piping hot water that a household could possibly use for £12 to £15 per week must be worth perusing…….if it actually works reliably.

Quotes for installation range from around £2500 to £3500.  I really do not want to pay this for something that will be yet another roof decoration in a few years!  The competing claims of the various fitters along with an almost complete absence of good independent data about their reliability, real world efficiency and running costs have left me unwilling to buy, despite wanting to.

So here are a few queries if anyone out there can help:

1)  Does anyone out there have any direct experience, good or bad, of any of these systems over a long period (say, 5 years or more)?
2)  What should such a system cost to install and to run (remember that I already have a good solar water tank)?
3)  Are there any other alternatives that I may not have considered yet?
4)  How much maintenance/ replacement parts  are they likely to require?

Links to the various companies mentioned are below:-






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