According to the Energy Saving Trust, four million households (15%) in the UK are off the mains gas grid and are reliant on other forms of fuel to heat their homes and to generate hot water. For these households, electric water heaters are a popular choice. These devices are not just for off-grid dwellers, however. Thanks to their unique advantages, they’re growing increasingly popular with households across the board.

Lauded for being inexpensive to acquire, easy to install, highly energy-efficient and requiring little to no maintenance, it’s no wonder that these water heaters are becoming more sought after. What’s more, these systems are available in a variety of power levels, sizes and colours, meaning it’s easy to get one to suit your needs and your home.

When it comes to the running costs, however, some people are worried that jumping to electric will see their electricity bills skyrocket. Is there any truth to this? In this blog, we explore how much electricity electric water heaters use and how they compare with gas water heaters when it comes to energy efficiency.

How much electricity does an electric water heater use?

hot steaming water running from kitchen tap

The amount of electricity that an electric water heater will use depends on a number of factors, including its size of the water tank, the temperature it is set at, how much water is used and how energy-efficient the model is.

However, you can find out how much electricity a specific system consumes by checking its nominal output. This is usually given in kilowatts (kW) or watts (W). Modern, energy-efficient instantaneous electric water heaters have a nominal output of up to around 10 to 12 kW. This means that, depending on the water heater you go for, they would consume between 10 to 12 kW per hour. To figure out how much this would cost you, you would need to find out how much your energy company charges you per kilowatt hour (kWh). The average price per kWh is approximately 14.37p. You would need to multiply the nominal output by the price per KWh to figure out how much electricity your system would use per hour.

Here are some example calculations:

If you opt for a 10 kW water heater:

10 kW x 14.37p per kWh = £1.44 per hour to run

If you opt for a for a 12 kW water heater:

12 kW x 14.37p per kWh = £1.72 per hour to run

If you opt for a new, energy-efficient wall-mounted electric storage tank to generate and store hot water, you can expect it to have a nominal output of between 2 and 6 kW. Using the average price per kWh (14.37p), you could expect to pay between 28.74p and 86.22p per hour for running this system.

Of course, the actual amount you’ll pay per month will depend on the amount of time you run your water heater for and this will depend on your personal consumption and how busy your household is. However, if you opt for a modern system with a high energy efficiency rating, you can expect not to have to run your heater as much as you would if you choose an older or less efficient model.

Which are more efficient - gas water heaters or electric water heaters?

Electric water heaters tend to be a more energy-efficient choice than older conventional gas water heaters for a number of reasons.

Firstly, an electric water heater only generates hot water when the water is actually required. Older conventional gas water heaters, on the other hand, consume energy by keeping water permanently warm, even when it isn’t needed. This results in energy wastage.

Secondly, in electric models, the distance between the hot water system and the tap is usually very short. This means that very little heat is lost. Gas systems tend to lose some of their heat through the pipework, especially if they are in an unheated part of the house, for example in the roof space, resulting in inefficient heat retention and energy being wasted.

Electric water heaters also give you more control over how much energy you’re using as you can pre-set the temperature and the flow rate. Some also allow you to monitor energy consumption. You can even get water heaters with automatic water volume controls and eco functions, which help to improve energy efficiency and keep costs down.

Although electric water heaters are more common in houses with no mains gas, flats and rented property, these systems are becoming more common as we move away from using gas and oil in an attempt to be more environmentally friendly. Switching to an electric water heater is one of the many ways that households can reduce their impact on the environment so these devices are worth considering if the time has come to replace your older conventional water heater.

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