Introduction: SOLAR WATER-HEATER Rainy Day Bypass.

In South Africa our state owned Electricity Corporation is call EISHKOM. Which means OUCH-OUCH!

We now have a new expression, STATE CAPTURE. I am no politician, but what I understand is that by paying the correct bribes, this is now totally run by the Gupta Brothers. They arrived here as poor immigrants / refugees? and now they surpass Bill Gates in riches.

To the man in the street it means that our electricity went up by 1200% while our income went up by 45%.


Understandably every person who is not on the Zupta Gravy Train, wants solar electricity and hot water.

With the electricity, we are waiting for Elon Musk to kill the energy inefficient lead acid battery, invented at the turn of the last century, to sell us affordable effective power storage. (Please sell us the poor man's bank!)

BUT.........luckily solar water heating works absolutely perfect with the cheapest technology. The vacuum tubes made a big difference in efficiency, but even cheap black plastic pipes make water boil in a few hours!

I built a system for under $40, and we have boiling hot water every day and even for two days after the sun goes away, to bring us rain.

But what if it rains for 3 or even 5 days in a row??

Here in the Kruger Park, it will be on the TV news, but many places in SA and in other countries, this is normal.


Step 1: When the Water Is Cold, Just Turn the Timer Switch on for 20 Minutes, and Then Have a Lovey Hot Shower.

How does this work? This is what I am going to share with you now.

I built this about 9 years ago, and last week it started dripping on my kitchen ceiling. I was surprised to find the 4mm thick galvanized steel fittings were leaking. I removed the unit for repairs, and decided to share the re-construction with you. I found that the part of the 40MM socket, where it was threaded a bit too deep, rusted through.

Step 2: The Rusted Nipple

To prevent this from happening so fast again, I picked the parts out with care, and I covered the whole unit inside with a very thick layer of the best rustproofing paint I could buy.

Step 3: Buying the Parts

I show a typical solar water heater right at the top, storing the heated water in an insulated water tank. Most modern ones has an electric element built in, but this is for the older ones, using what is still called a donkey. Originally the donkeys required a fire made under them every afternoon.

Mine uses 20mm PVC pipes. The unit should be fitted in the pipe that connect the top of the heater-panel with the top of the two Solar holes the the storage tank. Study the photo.

The hot water is lighter than the cold water and that is why it will move up that pipe and collect in the top of the water tank. By fitting the bypass heater here, it will create a flow, even on a rainy day, storing the heated water in the top, ready for use. .

I suggest you go to a hardware store, and start by buying a lower wattage geyser element. I used a 2Kilowatt one. THAT GIVES A PRETTY NICE SHOWER IN 20 MINUTES.

The one I got has a 32mm thread. I screwed it into a 32 to 40MM adapting socket, and then all the rest uses 40MM fittings. Loosely screw the whole unit together like on the photo. Fit the two 20mm pipe fittings as per photo.

You will also need a bit of HEAVY 20 amp wire. The new surfex cable worked fine for me. Also, not shown. a thermostat that fits inside the geyser element. See it on the wiring.

Step 4: Assembly and Rustproofing

I am not teaching basic plumbing here.

Screw everything together, tight, but not overtight, using teflon sealing tape or whatever they use in your part of the world. Now I plugged the two 20mm loose ends with paper, and found a temporary nylon screw-plug for the the element hole.

I painted the outside with block rustproofing, then I poured 3/4 cup of super rustproofing paint in, closed and shook it!

Then I drained the excess paint back into the can, and baked it two days in the hot sun. .

Step 5: Fit the Element

Now screw the element in taking care not to damage it or the fibre washer.

Step 6: Test for Waterproofing

Connect a pressure hosepipe from the garden to the unit.

Open the tap, and then close the open end with a thumb, checking for leaks.

Step 7: Prepare the Wires.

Prepare the wire well, as the element draws a lot of power, and any loose or bad fitting wire can cause arching and a fire in your house! Do not over or under tighten the terminals. The copper should by squashed a bit, but not get cut. If you do not have the knowledge, please show it to an electrician and ask him to OK it!

Step 8: The Wiring

Connect as per diagram. You can test it with a multimer, but not with power! Turn the thermostat to click on and off and then leave it at about 50 degrees.

Your unit is now ready for fitting or inspecting by a trusted / qualified person.

It is important that it be earthed properly.

Step 9: Fit It Into the Donkey.

My donkey is an old steel donkey, which is getting very difficult to find. They were commonly used in houses built in the 40 and 50's. working in conjunction with a coal stove.

It is wrapped in old blankets and sleeping bags, and keeps the water very hot for up to 3 days.

It is sitting in the ceiling above our kitchen and bathroom.

Step 10: Orientate It Correctly for Thermal Flow.

Orientate it so that the hot water will always rise. If there is only one place which is not running uphill, the whole system will stop working. Check the photo.

After you connected the wires, turn it on and watch the unit.

It should get hot to the touch, but not excessively so.

As the water heats it will rise and be replaced by cold water from the bottom. Once all the water is hot, the thermostat will turn it off.

Step 11: Connect the Power Wire and Switch.

I really and seriously instruct you to find a clockwork timer switch. They are cheap and work very well.

This one has been working for some 8 years as you can see from the dirt!

Whilst the thermostat will give protection against overheating, playing double safe with a house and lives is essential. Power the unit at a 15 amp- plug, running through the necessary circuit breakers and earth leakage.


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    2 years ago

    What a great way to warm your water!