There are so many electric showers on the market, it can be difficult to choose the one that's suitable for your bathroom. In this guide, we'll explain what kW ratings mean and the difference between manual and thermostatic showers.
What is an Electric Shower and how does it work?
Unlike a traditional shower which uses both hot and cold supplies, an electric shower only requires a single cold supply from your mains water. This water passes through a small unit with an electric heating element, which warms your water to to the desired temperature.
How easy are electric showers to install?
Replacing an existing electric shower with a new one is a reasonably simple job to do. This is because the pipework and electric supply is already in place. There are limitations however; the existing cable size will determine what kW shower you can install. See further down for cable sizes and kW ratings.
When installing a brand new electric shower from scratch there are plenty of things to consider. For starters, the shower needs a dedicated cable run to the main consumer unit (fuse board). This can be difficult to do without having to lift floorboards or hide the cable within the walls - especially if the bathroom is upstairs and the consumer unit is more than likely downstairs. There also needs to be a free space in the consumer unit for a new circuit breaker to be fitted to protect the shower. Then there's the water supply to the shower. On a new install this would ideally be done before tiling so the pipe is concealed within the wall. Electric showers only require one 15mm pipe supplying them that comes from the mains water.
What is kW and what do i need?
kW is a measurement of power, 1 kW = 1000 watts. Electric showers in the UK vary from 7 kW up to 10.5 kW. In simple terms, the higher the kW, the more powerful the shower will be. This is because the water is able to be heated up quicker, therefore passing through the shower faster than a lower power shower.
But it isn't as straight forward as going out to buy any shower. Different kW showers need certain cable sizes to supply the required power. Cable size is measured in mm².
● 7.2kW - 6mm²
● 7.5kW - 10mm²
● 8.5kW - 10mm²
● 9.5Kw - 10mm²
● 10.5kW - 16mm²
So if you're replacing an existing electric shower, it's important to know what size cable you have supply it.
Water pressure is a major factor in choosing an electric shower. The pipework supplying the shower needs to be 15mm minimum and have a working pressure of at least 0.7Bar to work effectively. During peak times your water pressure may be lower which can effect the shower pressure.
Manual or Thermostatic?
Manual electric showers are simple and straight forward. You set the desired temperature and the shower heats up to it. The problem with a manual shower comes when someone else in the house turns on a tap or flushes the toilet. The water pressure drops and the shower will either go freezing cold or scalding hot - either way it's unpleasant.
A thermostatic electric shower is designed to maintain water temperature within a +/- 2°C range so there isn’t a noticeable variance in temperature change when you’re showering. So if someone turns a tap on elsewhere in the house, the thermostat will adjust the temperature to suit the flow rate.
You'll find thermostatic electric showers are dearer than manual showers, but well worth the extra money for peace of mind and a more comfortable shower.