Why does my electric shower cycle between hot and cold continually?

Electric showers heat cold water on demand via an integral heater tank. Should the water inside the heater tank become excessively hot, a safety device known as the thermal cut out switch ( t c o ) is activated which isolates the electrical supply to the heater tank and allows the water to cool. Once the water has cooled. to a safe temperature, the heater tank's electrical supply is restored so the shower will again and deliver heated water.

Any build-up of dirt soap hair etc. in the shower head restricts the flow, meaning water cannot escape quickly enough through the shower and remains in the heater tank for longer than necessary. The water will then overheat and cool down. (cycling)

 To fix this problem, you should ensure that the shower head is cleaned on a regular basis, Also a kink or blockage in the shower hose will also restrict the flow and result in this symptom, shower hoses and heads are available with different flow rates so check if these have been replaced and revert to the originals, make sure the main stop cock and any isolation valves to the shower are fully open to allow a full flow of water..If this doesn’t work you will need to call us out to inspect the shower.