Solar hot water - Lukewarm response

My first test of my experimental solar hot water system ended in disappointment.

There are two pipes attached to the storage tank, one drawing cold water from the bottom, and one carring hot water to the top. Due to my overly hopeful construction technique, there was no way to remove the inevitable bubbles. The result was, as soon as the system started working, it would stop.

I managed to get from 12 deg C to 23 deg C but I had to remove the bubbles. That meant losing water and adding cold water to replace it. So I was back to square one again. I did that a few times and each time it would rise rapidly to 23 and then bubbles would collect again.

The other issue (actually there were many) was the flow was too low. If the system is working properly we should see the collector box being cooled by the water flowing through. Cooling one place means shifting heat to another. I was still getting readings around 70 deg C and I'm pretty sure they should have been more like 55 deg C.

I changed the top pipe entry point so that it no longer traps air bubbles. I'll test it again tomorrow. And I've just discovered I have a leak.