Most modern geysers in South Africa are high-pressure hot water heaters.
Never work on geysers yourself unless you are a licenced plumber and you know what you are doing! They are high-pressure vessels and can explode.
Home inspectors report that the most common defect in South African homes is an incorrectly installed geyser. Notably, this defect is potentially dangerous and is mainly a result of untrained, or un-supervised workers installing hot water heating systems.
Exploding geysers kill people in South Africa every year.
Temperature and pressure release valves
All high-pressure water heaters must have a temperature and pressure release valve (TPR valve). This valve controls two critical functions: pressure and temperature. Therefore, do not tamper with this valve!
If the thermostat fails and the temperature rises beyond 70°C, pressure increases. In this case, with the rising temperature, the TPR valve on the geysers will release if it is working correctly. Moreover, this happens either because of excessive heat or pressure.
If the TPR valves are faulty, the boiling point of water can rise above 120°C! The pressure will reach a point where the geysers’ pressure tanks rupture. At this point, the water turns into steam instantly. As a result, the 150 litres water in your geyser will now occupy 240,000 litres of space! This results in an explosion of the ferocity of a half kilogram of dynamite ( approximately 2½ sticks). Not only will the damage be excessive, but, as a consequence, lives can be at risk.
In my experience, about 4 in every 10 geysers have not been installed correctly, therefore, it is a good idea to have your’s inspected!
Also, during periods of water cutoffs, do not use hot water or open hot water taps! You will burn out the element!
Ensure that a home inspector or plumber inspects your geyser installation!
These videos show extreme cases of a hot water heater explosion:
Inspected Once, Inspected Right!®