The other night I woke up thinking it was raining really heavily. I looked out the window to see clear skies, so I popped outside to investigate. Along the side of our house I found a stream of water coming from our geyser (hot water tank) overflow pipe. It went on for about 20 minutes or so, which I can only imagine completely emptied the tank. This has happened before, but it happens only occasionally (maybe once every two or three months). When it happens though it will happen two or three days in a row. I don't think this is normal behavior for a geyser, and I'm sure it's causing higher power consumption. Why is my geyser doing this, and is it something that can be fixed?
The tank has a serious problem! Pressure is building in the tank and is released by the over pressure valve on the side of the tank and comes out the overflow pipe. This is not normal operation for this to happen! If over pressure occurs even once, it needs to be investigated! If you allow this to frequently happen you are inviting disaster. Get the tank replaced immediately!
Also if you have an expansion tank, the internal bladder may have erupted.