Geysers manufactured to SABS standards are strictly controlled in terms of their standing heat loss and the insulation requirements are regulated by SANS 151 (SANS – South African National Standards).
The maximum allowable heat loss for a 150lt capacity geyser (most common geyser size) is 1,377kW per 24 hours at a stored water temperature setting at 65 degrees C and no water is drawn off during the 24 hour period. This translates to a temperature loss of between 8 to 10 degrees C over the 24 hour period. A 150lt size geyser will take close on to 3 hours to heat from completely cold water (15 degrees C) to 65 degrees C, which equates to the usage of 8.72kW of electricity with a 3kW element and will cost approximately R14,38 (assuming R1,65/kWh), however one must remember that a geyser is seldom heated from completely cold, as not all the hot water is drawn off at once.
Let’s say the water in a 150lt size geyser has reached the temperature setting of 65 degrees C and the geyser is then switched off for 12 hours and no water is drawn off. This will equate to an approximate saving of 0,87kW @ R1,65 per kW, thus a saving R1,43 per day and if this practice is carried out every day over a month (30 days), the monthly saving will be R42,90 per month, not the high savings some may think they would make.
By switching off the geyser over peak electricity demand times (mornings and early evenings), you are assisting Eskom by load shifting, however saving little monetary wise. Switching the geyser ‘on’ and ‘off’ will cause no harm to the geyser.
The only real way to reduce electric consumption on a geyser, which will be of financial benefit, is to reduce the amount of water that is heated and drawn off i.e. reduce your hot water consumption, and reduce the temperature setting of the water on the thermostat. Ideal setting is 50 to 55 degrees in summer and 60 to 65 degrees in winter.
A geyser blanket will save on electricity but the saving is minimal. The saving will be more noticeable in winter months when the temperature in the roof plummets. Tests have shown that this has the potential to save up to 20% of the 2.6kW of electricity required to reheat the water if the geyser had been switched off for 24 hours. Installing a geyser blanket and insulating the pipe work can on average save a household of four people between R180 to R250 per annum, based on an electricity cost of R0.45c per kW.
Exposed pipe work on the hot water supply from the geyser can also be insulated with polyethylene foam lagging which will assist in some energy saving, particularly in winter.
It is advisable to contact an electrical merchant (store) to find out about the different makes and the size should be no less than 20 Amps. Ensure that the timer has a spring reserve or battery to prevent time loss during load shedding.
Direct System: the potable water in the geyser is directly heated by the solar collector.
Indirect System: the potable water is stored in ann inner tank with an outer tank surrounding the inner tank know as a jacket. The jacket is filled with a mixture of propylene glycol and water, which is heated by the solar collector and heats the potable water in the inner tank.
The solar geyser is installed at a higher plane than the solar collector. The basic principles of physics come into play where a liquid is heated it becomes less dense and rises, creating a thermosyphon circulation of the liquid between the solar geyser and the solar collector.
The solar geyser is installed at a lower plane (normally in the roof) than the solar collector. In order to circulate the liquid between the solar geyser and the solar collector, circulating pumps are required. In keeping with using solar energy, the pump is powered by a solar crystallite panel.
The array of solar vacuum tubes are more efficient, as the tubes are round and the sun rays will start heating the system earlier in the morning. A tube system also allows for the installations to face up to 40°C east or west where the flat panel has to face true north.
Very little maintenance is needed. The system should be checked for any visible leaks and the solar collector should be kept clean. The heat transfer liquid (dilution of glycol and water) in the Indirect System must be topped up if there has been a leak and the changed every two to three years.
A beeping alarm indicates an error has occurred. This error will not clear itself and the machine requires attention. The error code will be displayed on the control panel and the diagnostics of the codes is in the manual or on the back of the electrical control box cover.