Solar Water Heating Headaches 1


I just wanted to share our short story about our solar water heater experience separately from the catch-up blog post. But we feel like it might also be helpful to some of our Kenyan friends who might be considering a solar water heating solution for their home, project, or business.

This system was supposed to be fantastic- let the sun heat the water during the day and have hot water 24/7. We had hot water alright! It was TOO hot! And the pressure coming from the hot water system was more than than cold water system. So, we were struggling to get a good balance at the taps. The water was SO hot and so difficult to balance, we couldn’t even stand to take a shower, but of course we had to at some point. We were also having MAJOR problems with water leaks in the ceiling in various places because the hot water was expanding and contracting the pipes and leaving leaks. And the system had so much pressure (we thought from the extremely hot water), that water was constantly spraying out of the breather valve on the roof and wasting water all over the place.

After many failed attempts at trying different solutions to fix the problems, we realized that the people who had installed it really did not know enough about what they were doing in the installation. So, we sought out a solar water heating expert in Nairobi. He told us the company sold us a VERY good system, but there were some major key elements that the installers really need to learn and understand.

First problem was with the over-heating. Our solar water heating system has an electronic backup heating element inside the tank. This is there for during the rainy season when we do not get enough sun to fully heat the water in the tank with only solar power.  Sounds handy, right? But what if the heating element is constantly heating even when we don’t want it to?! Yea…oops. The wiring was done wrong with the switch. There is supposed to be a manual switch that allows us to choose when we want to turn on this electric element. Apparently, that switch was not wired correctly and the heating element had full power for over 2 weeks causing the water to be heated by the VERY hot sun and the electric element. No wonder it was SO hot! So, we wired the switch correctly and problem #1 was SOLVED!

The next problem was the pipes leaking. When our plumbers did the pipe installations, they were told by the solar salesman that they needed to install galvanized iron (GI) pipes for the hot water system. The other option here is to install ppr pipes which are some kind of hard plastic pipes that can be joined together by using a heat machine and then easily pressed together. So, originally we thought, “sure, hot water in ppr pipes might not be good since they could melt or leak due to the heat of the water inside them.” But then our GI pipes were leaking at almost all of the joints. When the solar expert came, he said, “not good. These GI pipes will always leak from the expansion and contraction of the joints when the pipes get hot and cold again.” So, we told him of our concern with melting the PPR pipes and he laughed. “The water can’t get THAT hot,” he said. He has installed these systems all over Kenya and used PPR pipes effectively with all of them. So, we ended up changing out all of the GI pipes in the ceiling to PPR pipes. Problem #2 of the leaky pipes SOLVED!

Then there was this matter of pressure. It would seem that we had way too much pressure flowing out of the hot water system and not enough pressure flowing out of the cold water system. Our expert told us that the pressure in both pipes should actually be equal. We currently had water coming directly from the main city source feeding into the hot water system and we had cold water being fed by gravity only from small storage tanks in the ceiling of the house. The pressure was not at all equal. We either needed to construct a very large water collection tank up on a tower outside the house and feed both temperature water systems with that tank. Or we needed to find a way to feed water directly from the main city water into both systems so that they had the same amount of pressure. The large tank tower was going to be VERY expensive and not something we really wanted on our property. Feeding both systems from main city line didn’t sound too difficult, but then our expert decided we needed to test the pressure coming from that source since we were having so much water spraying out of the top of the tank. He believed it was from too much water pressure, not just because the water was too hot and boiling out. Turns out he was right. With a nice pressure gauge, he found out that we were getting 8 bars of pressure from the line and this solar system should only receive 1 or 2 bars. We had 4 times the recommended limit! So, we introduced something called a Pressure Reducing Valve.

pressure reducingThis valve can be adjusted to only allow the desired amount of pressure into the house. Problem #3 of too much pressure SOLVED!

There was then the possibility that even with the electric heating element being off unless we needed it, that the water could still be too hot from the extremely hot sun in Kenya. So, the expert also recommended that we install a Thermal Mixing Valve.

thermal mixing

This valve can be adjusted to mix hot water coming out of the solar system with cold water before it even reaches the sink and shower mixing taps. This would ensure that the water does not reach a temperature that would till be too hot to mix at the sinks and showers. Problem #4 of extremely hot water SOLVED!

Then, there was one minor issue (not really a big problem) that the expert recommended that we fix. The water coming from the main city source often has quite a lot of dirt sediment in it. In fact, we do not drink the water from the taps. We filter all of our drinking water with our Berkey Water Filter provided to us by our good friend, Brian Sullivan. (If you need one, I’ll give you his contacts).  Because our expert knows all of this dirt is really not good for the hot or cold water systems in the house, we should install a small sieve.

seive

This sieve reduces the larger sediment pieces from the water before it enters the house making it better for the system in the house, a little easier on our filter, and safer for us.

All problems solved! And we are very happy now with our plumbing in the house. No more leaks, great pressure on hot and cold, and easy to mix the temperature for our desired needs. We even had a day recently with no water from the main city water and our storage tank/pump system worked great too!

shower

Perseverance won the day!

Comments

  1. […] also had a major headache with our solar water heating system. But that’s another story. Feel free to read it if you’d […]