In this article, we explore some of the common problems that can occur in electric showers, from faulty thermal switches to blocked shower heads.


Electric showers are one of the main types of showers in the UK, alongside mixer showers and the growing trend of digital showers.


These types of showers use cold mains water only for the water supply, and are also safely connected to the mains electric for power. The water enters the shower and, as the water is passed through the internal heater tank (or heating element), it heats the water up extremely quickly, providing instant hot water. Popular examples are the Mira Jump 8.5kW and the Mira Sport 9.0kW, the latter of which is a best-selling range across the country.


But what exactly can go wrong with electric showers? In this article, we explain some of the most common problems people encounter. You can also view our video on this topic below:



The most common problems with electric showers consist of:


  • Thermal switches failing or cutting out. The thermal switch is an important safety feature on electric showers; its purpose is to turn off electrical supplies to the heater tank in the event that the water temperature gets dangerously hot. In such cases, the thermal switch cuts off the elements (which are the actual heating parts, like the elements in a kitchen kettle) and the water will go cold. Once the water temperature cools down sufficiently, the thermal switch will allow the heating element to function normally again, providing hot water. In some situations, you may notice a hot/cold/hot/cold cycling scenario, usually caused by a blocked shower head creating back-pressure internally. Clean and descale the shower head and this may solve the problem. If it doesn't, you may have to consider inspecting and replacing the heater tank due to limescale build-up, as this presents the same symptoms. If the shower is completely cold, the thermal switch is likely faulty: a multimeter can confirm whether there is continuity - if not, it'll need replacing. See our article here explaining how TCOs work in a shower.
  • Blocked shower heads. A build-up of limescale and debris on the nozzles or inside the shower head can cause blockages, preventing water from exiting through the head properly. This in turn can cause back-pressure to build, leading to other problems, such as pressure relief devices blowing. Simply clean the shower head using a descaler or replace it.
  • Kinked or damaged shower hoses. Damaged shower hoses - like blocked shower heads - cause a build-up of back-pressure that can lead to issues internally in the shower. Unfortunately, a kinked or damaged hose, especially those that have collapsed inside, will generally need to be replaced.
  • Limescale build-up in heater tanks. Because heater tanks operate much in the same manner as a kitchen kettle, limescale build-up is unavoidable. However, if the scale becomes too great, the heater tank may develop faults. Manufacturers do not recommend descaling a heater tank for safety reasons; instead it should be replaced.
  • Pressure relief devices blowing. Another safety feature of electric showers, these will fail if the internal pressure in the shower builds up. See our full article on replacing pressure relief devices for more information on this common issue.
  • Seasonality. While not strictly a fault or problem, we do get a lot of customers ask us why their electric shower runs colder in the winter months. See our full article on the seasonal effects on electric showers for more information.