Solar Water Heater

I have tried to do it last year for our Malacca's place, but it didn't work out due to distance & time contraints.  This time, it finally works.  However, it wasn't easy, as it took many trials to finally get it done.

I built it using 1/2" PVC pipes(3 sticks of 6m), and painted it flat black to absorb as much heat as possible.  Originally trying it out on the ground to make sure things work.

First trial, it fails, water didn't seem to be circulating like described online.  Thermosiphon was supposed to work and get the water circulating, it didn't.  I opened the loop to test whether water inside was hot, it was, but it just didn't circulate up to the tank.  Finally, I figured out that it could be the air bubble locked in the pipes.  So, I flushed the air out from the pipes by inserting a water hose in the 'cool water' outlet.  I could feel some warm water flowing out from the 'hot water' inlet.  So, my test model worked.  It was time to put the real setup on the roof top.

So, I put a bigger water tank reservoir, it is for 8 people to use.  I put it on the roof of the 1st floor.  Didn't put on the 2nd floor, cause it was too risky to climb that high.  I flushed the water out to clear the air bubble.  I could feel the warm water flowing out.  Good.  It was about 7pm and it was on Friday.  I had gotta go back to KL.  So, no actual test till the next week.  However, I had already spotted few leaks on the copper pipes, but nothing could be done cause it was too late in the evening to do anything.

Came Tuesday, repaired the few leakages.  It was time to test, but it wasn't too sunny and hot.  I told myself, tomorrow, I should be getting warm water.  Wednesday came, and there was a little hot water as you could feel the copper pipe was getting warm by the water flowing through.  Unfortunately, the hot water was only for a very brief moment, then it was constant cool water.  In addition to that, water pressure was kind of low.  I was like, this is not good at all.  Even if the water was hot(which it wasn't), the whole hot water shower experience wasn't going to be a good one due to the extreme low pressure.  On top of that, I have installed a rain shower head!

Suddenly, it hit me that the air bubble locked in the pipes might be causing the low pressure.  So, I opened both shower heads, one on the ground and one on the 1st floor.  This solved the problem and water was flowing quite strong.  Unfortunately, no hot water!

I had to climbed out from 2nd floor to the roof, so I tried to limit my climbs.  I put my finger in the pipe where the hot water is supposed to flow out, I couldn't feel the flow.  I could feel it when it was on the smaller tank.  Then I noticed the PVC pipe's position was a bit off, it was supposed to be on slope so that hot water could flow up.  A few of them have fell, so I thought that was the problem.  Painfully took the 'collector' apart to fix.  Yet, no hot water was flowing through.  I suspect it was due to the pressure again, cause this time the hot water 'inlet' to the reservoir tank was kind of high.  I suspect the hot water wasn't hot enough the whole way to flow up to reach the tank.  Water might have been cool by the huge volume in the tank.  My next solution was to use a water pump to force the circulation through the heat collector pipes.

You can see the black wire, which is the pump's wire.  I connected it to a timer to only turn on from 12pm-5pm.  The blue tank is reservoir for air conditioner's water.  I am using it for ground & 1st floor's toilet flush.

It worked!  The tank was slowly warming up, but it isn't hot.  It is comparable to our instant water heater's temperature.  I want it to be 'hot' so that someone can bath with the hot water mixing with the normal water.  This will save the hot water usage, and allows for more people to take the hot shower.

I had just gotten it to work for 2 days, so I will have to test it next week to see how hot it could get after being cooked for several days.

So, it has been more than a month, so far it is working OK.  Water is warm, and no one has complaint about it.  One problem I did notice is, I have connected 1 single outlet to the 2 bathrooms.  As a result, when ground floor & 1st floor are both showering, 1st floor will suffer from low water pressure.  The solution is to have 2 outlets to each bathroom, not sharing 1 pipe.

What I have learned?

1. always flush the pipes to clear the bubble whether it is the heat collector or the shower
2. make sure the outlet & inlet to the heat collector are facing the sun.
3. circulate water to flow through the heat collector
4. do not share pipe to the bathroom.  Use individual pipe for each bathroom to have uninterrupt water pressure.