We have a Geyserwise system connected to our Geyser and occassionally see an error E1 or E9 in the Geyserwise display.
The E1 error occured after a water outage and I had turned the Geyser power off, until the water supply had returned and I had been able to refill the Geyser with cold water by running the hot water tap.
When I turned the Geyser power on I saw the E1 error. The Geyserwise manual says that the fault is a failed element or ground leakage. I discoved that by turning the Geyser power off and back on a couple of times resolved the error. I surmised that turning the Geyser power off caused an inrush current to the element that the Geyserwise control box determined was a ground fault. If the E1 error does not resolve after power cycling the Geyser then it does mean that the Geyser element has probably failed and you’ll need to call in a plumber.
The E9 error happens frequently and is also a result of a water outage when there is not enough pressure to push water through the system or if no hot water had been drawn from the system during a hot day.
The E9 error was fixed after the water was restored and the hot water tap was turned on to bring cold water into the tubes.
This also applies if the hot water is not drawn when the solar tubes are full and so simply running the hot water for 30 seconds will fix the E9 code.
When the E1 or E9 code appears in the display, the Geyserwise pump will be automatically shut off so as not to damage it. However this means that you won’t have any hot water until you resolve the errors.