How Does an Electric Shower Work
So, you want to know about Electric Showers you say?! Here goes!
Electric showers are a very popular shower type because they are relatively easy to install and are also not reliant on your combi boiler (or other boiler) working to provide hot water. This can make them a great redundant option in case your boiler breaks at a key time. They require a cold water supply and usually a thick cable installed by an electrician because they draw a lot of current.
Source! As well as being a qualified Gas Engineer I was a Part P qualified electrician to enable me to do electrical work on jobs.
Technical Facts about Electric Showers
Essentially an electric shower is like a small kettle, with a cold water supply being passed through a heating element and a control pcb that regulates the temperature as per the set position on the dial on the shower front. This causes the water to be heated up very quickly so it is hot when it gets to the shower head after a short warm up period. In fact electric showers can be VERY hot indeed compared to a normal combi powered shower, even though their temperature is regulated.
Where Can Electric Showers be Fitted?
Condensing boilers are a lot more efficient because they recycle the heat from the burner exhaust fumes back into the heating system to add to the water temperature. This is similar to how a turbo on a car engine recycles the heat from the exhaust gas to take more energy out. It is a very efficient system; or as efficient as a burning process can be (not that efficient in reality). Also pumps on modern boilers are modulating, so they can pulse on and off when the system needs flow or is up to temperature.
This is primarily because condensing boilers work much more efficiently at lower flow temperatures.
Requirements to fit an electric shower?
Electric showers do have some minimum requirements that have to be met before they can be installed.
Incoming water requirements for electric shower
Firstly you need a minimum of 14psi (aka 1 bar) of water pressure and a minimum flow of 8 litres per minute. The maximum pressure you can have is 10bars of static water pressure which is unlikely in most locations. In the event you do have such a high standing pressure, the plumber can install a pressure restrictor prior to the electric shower to meet the showers maximum incoming water pressure limits.
As well as requirements in relation to the water supply, not surprisingly there are requirements for the electrical supply as well. You should consult a certified and reputable electrician to install the electrics if they are not already present, but we will outline the electrical requirements below.
Electrical Safety and Installation for an electric shower
There are a variety of safety checks and precautions need to follow to safely install an electric shower into your home:
Firstly be sure your consumer unit (also known as fuse board) is capable of providing the required current .
The mcb size must be equal to or the nearest size above the kilowatt rating of the shower see table below. Older type wire fuses are not recommended for electric showers
- 7kW = 32amp mcb
- 5kW = 32amp mcb
- 8kW = 40amp mcb
- 5kW = 40amp mcb
- 5kw = 40/45amp mcb
- 5kW = 45/50amp mcb
NICEIC states
“Electric showers require their own electrical circuit, which in general will have the highest electrical demand out of your household appliances. All circuits in a bathroom must be protected by a RCD (Residual Current Device). They will need to be connected to the consumer unit and protected by an RCD. The cost of fitting an electric shower will depend on whether the consumer unit requires updating to comply with current safety standards. Building regulations require an adequate means of ventilation. An extractor fan is essential and will help cut down steam in the bathroom.”
What Cable Size for an Electric Shower?
It is wise to get 10mm cable installed for your shower unit. It is ok to use smaller cable with lower wattage showers but a larger cable gives you some overhead and also allows you to upgrade the shower should you ever want to .
What Switch do I need for an Electric Shower?
All electric showers should be operated with a double pole pull cord switch that has a visual (eg words) off/on indicator. The
