Most modern geysers in South Africa are high-pressure geysers (hot water heaters). Never work on the geyser yourself unless you are a licenced plumber and you know what you are doing! Geysers are high-pressure vessels and can explode.
Home inspectors report that the most common defect in South African homes is an incorrectly installed geyser. This defect is potentially dangerous and comes about when untrained, or un-supervised workers install the geyser.
Exploding geysers kill people in South Africa every year.
Temperature and pressure release valves
All high-pressure geysers must have a temperature and pressure release valve (TPR valve). This valve controls two critical functions: pressure and temperature. Do not tamper with this valve!
If the thermostat fails and the temperature rises beyond 70°C, pressure increases. With the rising temperature, the TPR valve will release (either because of excessive heat or pressure), if it is working correctly.
If TPR valve is faulty, the boiling point of water can rise above 120°C! The pressure will reach a point where the pressure tank ruptures. At this point, the water will vaporize instantly. The result is that the 150 litres water in your geyser will now occupy 240,000 litres of space! An explosion occurs of the ferocity of a half kilogram of dynamite ( approximately 2½ sticks). The damage will be excessive. In addition, lives can be at risk.
In my experience, approximately 40% of geyser installations do not comply with the SANS 10254 specification. Furthermore, of that 10 % were dangerous!
Furthermore, during periods of water cutoffs, do not use hot water or open hot water taps! You will burn out the geyser element!