Installed in August of 2005 my SDHW system has been a learning experience. After storing 2 salvaged flat plate collectors from a 1970's system and reading up on several system designs in Home Power magazine I made the leap. After building a tube within a tube heat exchanger that was featured in Home Power I was ready to go. Second, I say second because it took me two times to learn that the domestic side water loop would require a bronze circulating pump to survive the high lime content in my non softened water supply. Then everything ran like clockwork and provided over 50% of my hot water needs (100% during the summer months)for the next 10 years.
Year after year all was well until around November of 2015 and I noticed that the system was not pumping. Thinking that the problem was with the anti freeze filled solar loop I did not want to mess with this until warmer spring weather. So I waited until last week. Then I noticed that there was a small black burn mark on the circuit board where a relay for the differential temperature controller was. After replacing the relay still no go. Now I had the problem zeroed in as a locked pump that allowed high current to fry the relay. The plan was to replace the hot side loop antifreeze side and pump.
After draining the system I was ready to replace the pump and refill however the pump was just fine.