Using storage heaters and immersion heaters correctly

Storage heaters are a type of electric heater. They’re also called night storage heaters.

Storage heaters are designed to work with time of use tariffs like Economy 7 that have different prices for electricity at different times.

They use cheaper electricity during ‘off-peak’ times to store heat. You control when the storage heater releases heat during the day.

It’s important to make sure your storage heater is set up correctly so you don’t pay more for electricity than you need to.

If you have storage heaters, it’s likely you’ll have an electric immersion heater to heat your water. You’ll need to set this up correctly as well.

Check your electricity tariff

If you have storage heaters, you’ll usually be on a time of use tariff. A time of use tariff means you pay different rates for your electricity depending on the time of day. Electricity costs more during ‘peak’ times and less during ‘off-peak’ times. 

The most common time of use tariff is Economy 7, which gives you electricity for:

• a below-average price for 7 hours at night - the off-peak price

• an above-average price during the day - the peak price

There are other time of use tariffs  - for example, Economy 10.

If you have a radio teleswitch meter

If you have a time of use tariff, you might have an electricity meter that uses a radio signal to switch between peak and off-peak rates. These are called radio teleswitch (RTS) or dynamically teleswitched (DTS) meters.

You’ll need to have your RTS or DTS meter replaced. This is because the radio signal is being switched off.

Your electric heating and hot water could stop working if you don’t have your meter replaced before the radio signal is turned off.

Check if you need to replace your meter.

If you don’t know what tariff you’re on

Check your electricity bill. If you’re on a time of use tariffs, you’ll see:

• 2 or more prices ‘per kWh’ for your electricity - they might be called the ‘day’ and ‘night’ rate or the ‘peak’ and ‘off-peak’ rate

• 2 or more sets of electricity meter readings

Talk to your electricity supplier if you’re not sure what tariff you’re on.

Check the times your electricity is cheaper

If you’re on Economy 7, you’ll usually get your 7 hours of cheaper electricity sometime between 11pm and 8am.

The exact times depend on your supplier or where you live - contact your supplier if you’re not sure.

Your off-peak times might  change when the clocks change. For example, your off-peak times might be midnight to 7am in winter. They would change to 1am to 8am when the clocks go forward in March.

If you’re not on a time of use tariff

Talk to your electricity supplier. Tell them you use storage heaters and you want to make sure you’re on the right tariff.

Tell them how much you use your storage heaters so they can help you find the best tariff for your situation. If you have storage heaters but rarely use them, a time of use tariff might be more expensive.

Using your storage heater

You might have a storage heater that has 2 dials. The numbers on the dials usually go up to 5 or 6.

Example

This is an example of an older storage heater with manual controls. 

You might have a storage heater that has buttons and a digital display.

Example

This is an example of a modern storage heater that can do some things automatically.

Make sure your storage heater is safe

Don’t cover the surface of your storage heater or put things too close to it. For example:

• don’t hang clothes or washing on your heater

• don’t put furniture directly in front of your heater - leave a gap of at least 30cm (or around 12 inches)

• if there’s a window above your heater, don’t let curtains hang too close to the top of the heater - leave a gap of at least 7.5cm (or around 3 inches)

If your storage heater isn’t working

If you rent your home, your landlord is responsible for making repairs to your heating. Tell your landlord if your storage heater isn’t working and needs to be repaired.

Get help with repairs if you rent from a private landlord.

Get help with repairs if you live in social housing.

If you own your home and need to find someone to repair your storage heater, make sure you find a trader you can trust.

Replacing storage heaters

Older storage heaters with manual controls can be less efficient and cost more to run.

If you’re thinking of replacing old storage heaters, you could:

• get a more modern storage heater - ‘high heat retention’ storage heaters are the most efficient

• get connected to the gas grid and get central heating - this might not be possible if you live in certain places

• replace storage heaters with a heat pump - this is a low-carbon way of heating that uses less electricity but can be expensive to install

You might be able to get help with the cost of a new storage heater or heat pump, or getting connected to the gas grid and getting central heating. Check if you can get help making energy efficiency changes to your home.

Using immersion heaters to heat your water

If you have storage heaters, you'll probably have a hot water tank or 'cylinder' with two immersion heaters. 

Immersion heaters use electricity to heat your water. They look like a metal loop or coil and sit inside the hot water cylinder. 

The main immersion heater at the bottom of the cylinder heats all the water. Check if the main immersion heater has a timer - if it does you should set it to come on during off-peak times. An hour or two before the end of the off-peak times should give you enough hot water for the day, but you can set it for longer if needed. If there's no timer, the heater should run during off-peak times automatically.

The second immersion heater is further up the cylinder, so it heats only the water near the top. It usually has its own controls labelled 'boost'. If you have a time of use tariff, this uses the more expensive peak rate electricity.

Saving money with immersion heaters

It can be very expensive to use an immersion heater. Make sure your immersion heaters are only on when you need them.

If your main immersion heater has a timer:

• make sure the heater is set to timer mode 

• check that it’s set to come on during off-peak times

To make sure the heater is set to timer mode, check if there is a switch that can override the timer. Set the switch to use the timer - this is sometimes labelled with a clock symbol. If the switch is set to ‘1’, the heater will always be on. If it’s set to ‘0’, the heater will always be off.

Check the clock is set to the current time so the immersion heater comes on when you want it to. This is different to setting the timer. If you have a mechanical timer, you might have to turn the dial so the arrow points to current time. If you have a digital timer, check the instructions for how to change the time if it isn’t obvious. 

Check the manufacturer’s website - they might have a manual or guide for your timer. You can also search online for videos showing how to use your timer.

If your main immersion heater doesn’t have a timer, you probably won’t be able to control the times it switches on and off. However, it will automatically use the cheaper off-peak rate of electricity.

Try to avoid using the boost controls. If you run out of hot water during the day and your immersion heater has a timer, set the timer to come on for an extra hour during the off-peak times. 

Make sure your hot water cylinder is well insulated. Find out about insulating your hot water tank on the Energy Saving Trust website.