This is the time of the year when the calls start rolling in. “I have a single tank solar water heating system and the water heater has stopped working.” This is not a service call you should need to run out on.
Using a standard electric water heater for both your solar storage as well as providing your back-up heating has many advantages including; reduced floor space, ability to use standard tanks, less standby losses from the tank, better heat recovery, and less cost. But now we come to the rub. Electric water heaters have a thermostatic breaker built into the top element. When the thermostat senses temperatures over 170° F it automatically trips this safety breaker. This breaker is designed as extra protection in case you have a run-away element in your tank to keep the system from getting too hot.
Frequently a solar water heating system will supply 100% of your hot water needs during May through September. If at any time during that period the top of your tank exceeded 170° F the tanks thermostatic breaker will trip. As the cooler and cloudier weather sets in the back up element is no longer able to kick in and you receive a service call. Fortunately, the fix for this problem is simple and within the reach of even the least proficient home-owner.
Simply remove the cover plate over the upper element, depress the red button with the eraser of a pencil and voila you are back and running again. (see picture)
So next time you get this call don’t fret and think about the little red dot.