Geyser installations are often incorrect
An incorrectly installed hot water heater is the most common defect discovered by HouseCheck inspectors in South African homes. These defects can be very dangerous and clearly result when untrained, or un-supervised workers are left alone in the roof cavity to do the geyser installation.
Most new geyser installations are typically high pressure (400-600kpa) system – by far the most common type in South Africa. Vertical geysers are different although much of the description still applies. Low-pressure systems (100kpa) are significantly different but are fairly uncommon now.
Components of a hot water heating system
Drip Tray: The geyser sits in a tray made of plastic or steel. Since June 2001, the drip tray is not optional. The tray must be fitted with a 40mm PVC waste pipe that drains the tray by piping the water out of the house.
Vacuum breakers: These are small brass components mounted at the 30cm length of pipe. They two vacuum breakers stand vertically about 30cm above the geyser. These are important. They prevent the water siphoning out the geyser when the cold supply is stopped.
Shut off valve on the cold water side: The cold water side is the side that directly connects to the drain cock.
Temperature and pressure safety valve (T&P Valve): Mounted on the geyser towards often on the opposite side to the drain cock. This is a vital component. This valve should have a 20 mm metal (copper or steel) pipe connected to it and the pipe must lead directly out the building. This vent an important safety feature of the whole system. It must be made of copper or steel – not plastic. The pressure rating valve must match the pressure rating on the geyser.
Multi-valve (pressure control valve): This is a water pressure control valve fitted to the cold water supply to the geyser. The purpose of the pressure control valve is to “balance” the water pressure of the hot and cold water supply to baths, showers, and basins. For a balanced system the cold water supply to baths, basins, showers etc must be taken off the supply between the pressure control valve and the geyser. The pressure control valve reduces the cold water pressure to the same pressure of the hot water coming from the geyser. Sometimes plumbers will locate the pressure control valve outside of the house – where the cold water supply enters the house. This is fine. Mostly however the multi-valve will be found in close proximity to the geyser. The pressure control of the multi-valve is designed to release excess pressure and may, therefore, drip when water is drawn through the valve. Each geyser must also be fitted with a pressure control valve. As most geysers have a maximum working pressure it is vital that the pressure is controlled in order for the geyser to have a longer life span. If no pressure control valve has been fitted then the geyser guarantee will likely not be honored.
Note: If the multi-valve is located inside the roof cavity, then a 13mm overflow pipe extending to the outside of the house, must be fitted to the multi-valve.
Electrical isolator switch: Should be within 1m of the geyser. This was not a requirement on old geysers. The geyser also has to be earthed. There should be a cover over the thermostat and element. These are often just left lying next to the geyser.
Thermostat: Regulates the water pressure inside the geyser. A good temperature for household use is 60oC.
Self-sacrificing anode: Anode rods that come installed with geysers are generally are made of magnesium or aluminium that is wrapped around a steel core wire. Water heater anode rods are screwed into the tank. Because the rod is made with a higher current potential than other metals in the water heater, it will ensure that the galvanic current flows from the rod to other exposed metals, preventing their corrosion. In other words, the anode rod corrodes and not the tank or the element. The anode rod is “self-sacrificing.” When there’s no sacrificial metal left on the anode, the tank can rust out. Anode rods generally last about five years but this depends on the quality of the water and how much water travels through the geyser. Not replacing a depleted anode rod will shorten the life span of the geyser.
Plumbing piping: The geyser may be fed with polycop (plastic) pipe – up to the shut-off valve, but the pipe into and out of the geyser must be copper or galvanised steel. The PCV and T&P vent pipes also have to be steel or copper, especially the T&P vent. The hot water should be carried in copper, steel or suitably rated (70 degrees) plastic or metal-sheathed composite pipe.
Correct geyser installation image – courtesy Kwikot