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How to know if your geyser is faulty

During this past week the main switch tripped on my distribution board and - after some investigation - it was sourced to the geyser. This is the first time that this has occurred with the geyser, so of course I did some research to discover why this would happen.


No hot water

The following inspection should be made:

  • The circuit breaker at the distribution board is switched on and that the isolator at the geyser is switched on [see diagram below].

  • Municipality switching times, as the ripple relay may have caused the electric water heater to be switched off.

  • The house may have a load shedding relay and the geyser may have been switched off by the shedder.

If the above are all in order, either the thermostat or element is faulty and should be attended to by a qualified electrician. This is fairly common in a geyser that is more than 3 to 4 years old and is caused by many factors.





Not enough hot water

The most common explanation for lack of hot water is due to the geyser being emptied. Check the size of the geyser and the number of outlets which are being fed by the geyser, bearing in mind that a standard 1700mm bath, when filled to the overflow, holds 195 litres of water. Where a shower is utilized, the average showering time of each user, bearing in mind that the average shower rose can deliver between 15 litres and 20 litres per minute.

Use a Geyser blanket to make your Geyser more energy-efficient and save on electricity bill.

Other reasons for lack of hot water could be extremely cold weather {and where pipes are unlagged or insulated] and the addition of a municipal ripple or load shedding relay.

Adjust temperature setting

Check the temperature setting on the thermostat. Where set at increase by 5 degrees C until satisfactory temperature is reached.

The maximum setting on a thermostat is normally 70 degrees C, but this is extremely high. The average setting is around 50 to 55 degrees C.


On newer geysers, the thermostat cuts out when a high temperature is reached. The cut out also activates when there are power surges or fluctuations which exceed specified amperage of 20 amps.

Refer to the table to determine the amount of water used per bath.


No water from hot water taps

Check that there is water supply to the geyser. All modern water heaters operate on a push through system, i.e. water can only be drawn off if cold water is introduced to it. If municipal water supply is interrupted for any reason, water will not enter the geyser.

Continuous overflow of water

If water drips from the expansion relief, try and determine the volume of water. Water expands when heated and the volume of expanded water is directly proportional to the size of the geyser and the thermostat setting. Expansion can vary approximately 10% of the volume of the geyser per day.

If the volume expanding exceeds this, establish whether the house has balanced pressure. The term "balanced" refers to the cold water take off after the pressure reducing valve.

In an unbalanced system where common tap mixers or appliances are using hot and cold water simultaneously, cold water may tend to force the hot water back into the line, which in turn will over pressurize the geyser and cause the expansion relief to flow. The combined expansion relief pressure reducing valve can be serviced with replacement parts in the event of excessive release of water.

Both the expansion relief overflow and the safety valve outlet must be piped to the outside by means of copper pipes, and insulated where freezing can occur.

Geyser leaking from tank

Check that all plumbing connections are secure and that the safety valve is piped to the exterior.

Inspect the Flange Gasket [left] for signs.

Inspect the seams at the front and rear of the geyser and look around the base for any signs of damp or water stains.

It's important to check for water leaks on pipe connections, valves and the area below the geyser.

ABOVE: Deteriorated Flange Gasket [see diagram below].

If your geyser doesn't already a one, a drip tray [see diagram below] under the geyser will catch any small water leaks and protect the ceiling. A drip tray should have a drain pipe to the exterior of the roof space.

Always keep your proof of purchase which serves as your guarantee to assist us should you need to contact the manufacturer or a qualified plumber.

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