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Q&A with Handy Mac: Joan has a solar heating problem.

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For some or other reason we have a 10-tube system and not a panel system.

Q: For some or other reason we have a 10-tube system and not a panel system.

I use very little water so the system overheats. On some hot days it goes to 840°C, and then the geyser-wise control goes ballistic. I assume it is trying to tell me the geyser is overheating.

To solve the problem (bring down the heat) I run some water out of the geyser. But now, with the water shortage, that is no longer an option.

Last year, after consulting a solar company, they removed five tubes in January. Then I had to have it re-installed in May. Even after removing the tubes the water in the geyser somehow still went up to 800°C.

It cost me R1197 for a “service”, R969 to remove the tubes, and then R862 to put them back.

Besides the cost of this exercise, it just does not seem right and it does not seem to be a solution. The tubes can also break from lying around. Last week, when we had that terrible heat, the problem was back.

The solar company suggested replacing the tubes with a panel – cost about R9000.

They say the panel won’t overheat. I am not so sure because I am told that in summer many people cover some of the panels to stop overheating.

One does not know who can give you an honest opinion to solve the problem as everyone just wants to sell you a new system.

Do you perhaps have a view on this matter, or can you perhaps recommend someone who can give me a view on what I should do?

A: This question from a woman to whom I owe an awful lot, kicked me into gear to start looking at solar, as I had promised. I searched through my contacts, remembered my old mate Jacques, and asked him to comment:

The problem here is tubes. This is a very good concept but it is too efficient for our climates (Africa), and only good for European conditions.

If not much hot water is used (because we have a water crisis in Cape Town) the system will overheat. The mail sent to you is correct, but it does seem the cost Joan paid is high.

The geyser wise is correct and will send out a warning (usually E5) because water is very hot.

I can only suggest the system be covered. I will do this for free for Joan with covers that go over tubes. She can turn them over in summer and again in winter (no need to remove them).

In short Don, don’t install tubes. Flat plate collectors are the way to go. No worries and no overheating. We also do DC systems that don’t require plumbing, but will chat when we meet.


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