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Troubleshooting Solar Water Heaters

SHW systems are fairly simple appliances—not as straightforward as a tank-style water heater but nowhere near the complexity of a car. Seeing, hearing, smelling, and touching components (carefully) can assist in diagnosing problems before any troubleshooting equipment and tools are used. Experienced technicians use their senses to determine the status of a solar water heater. Unusual, high-pitched noises and burning odors are associated with bearing wear from the pumps. Burning smells can also indicate electrical problems, such as burned motor windings, loose connections, or damage from excessive voltage or current. Visual inspection can reveal controller malfunction, leaks, and fluid levels.

If all appears normal after a quick inspection and the sun is out with the pump(s) energized, measuring the temperatures of the collector loop supply and return can provide valuable information. If pipe temperatures allow it, feel the two pipes, with one hand on each pipe. If pipes are too hot to touch (above about 120°F), measure their temperature with an infrared thermometer. A noticeable difference in temperature between the two pipes indicates that the collectors are adding heat—the system is working.

Cold supply and return pipes are a symptom of no flow—check the pump(s) or controller first. Both pipes being hot and at the same temperature is likely only to occur in a system with an external heat exchanger. This indicates that the collector loop pump is operating and the controllers have turned it on but that the heat is not being exchanged to the home’s potable water. A malfunction in the domestic hot water (DHW) pump or an obstruction on the DHW side of the heat exchanger is indicated. More detailed symptoms are component-specific.