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Stellenbosch prof warns of exploding solar geysers in Cpt


gallderhen
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I suppose it is possible. But I learned something with cars. The trouble doesn't start when the water is boiling. The trouble starts when there is no more water to boil. The reason the water boils is because it is absorbing the heat and changing state. As long as you have water that can boil, you are usually okay. I would think that most thermo-siphon systems will not allow water to drop so low that the panel itself is left without water.

I suspect it also depends on the kind of system you have installed. I have no fear that anything bad is going to happen to my flat-panel thermo-siphon system.

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  • 2 weeks later...

Jip, I have EV tubes so I have that problem.

There is a setting on the controller, like when one is away on holiday, to switch the system "off". What it then does is recycles the hot water at night to cool it off for the next day.

Hope that would work if I hear the alarm when it overheats, and I switch it to Holiday mode.

Lame as can be but it is either that or covering the tubes.

OR, I find a way to connect a rainwater supply to the geyser using a pressure pump which could then solve the shower issue if / when Cpt runs dry.

Like if there is pressure, use municipal water. If there is none, auto switch over and use pressure pump and rainwater. 

Is there a BMV for water pressure, to use the relay? :D:D:D

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53 minutes ago, The Terrible Triplett said:

Is there a BMV for water pressure, to use the relay? :D:D:D

I'm hearing noises about legality of having such dual sources and the danger of backfeeding into the (water) grid when the pressure is down. Essentially, the same problem we have with electricity :-)

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9 hours ago, plonkster said:

I'm hearing noises about legality of having such dual sources and the danger of backfeeding into the (water) grid when the pressure is down. Essentially, the same problem we have with electricity :-)

I heard word in all the noises that apparently one needs to also install a V-Valve. it is blueish and rather expensive and what it does is it stops the flow back to the main supply, very similar to a non-return valve, if you have a "water-tied" system? 

Luckily one needs no engineers report yet, but that may be on the cards too.

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3 hours ago, The Terrible Triplett said:

one needs to also install a V-Valve

Yes, it needs a low pressure zone in the middle so that it is impossible for water to flow backwards into the supply. It's not really old news, this sort of thing is done frequently at irrigation setups where the fertilizer might be dissolved in the water. Last thing you want is for that to leach back into the supply.

If your municipal supply runs via a float valve into a backup tank, and you have a boost pump after that (ie no direct connection), then by definition you have a sufficient air gap and no backflow is possible. But if the pump breaks you have no water.

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On 10/27/2017 at 3:11 PM, gabriel said:

the municipal water meter incorporates a one way valve

I don't think that is sufficient. Those valves don't always seal fully, and if it is of the flapper kind, some water will flow past it before the flapper... uhm... flaps shut. Depends also how the meter is installed, if it isn't fully level, gravity might hold it open far enough that you can treacle a slow feed back.

Personally, I think a big ball valve is sufficient, but operator error still exists.

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3 minutes ago, gabriel said:

to tell the truth, i'm more concerned about their water getting into my system than vice versa :D

Reminds me of the old Microsoft joke.

Apparently, if you take a Microsoft Windows CD and play it backwards, you will hear satanic messages. This is however nothing compared to what happens if you play it forwards. Then it install windows!

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