Using storage heaters and immersion heaters correctly
This advice applies to Scotland. See advice for See advice for England, See advice for Northern Ireland, See advice for Wales
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.
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.
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.
This is an example of a modern storage heater that can do some things automatically.
Using a storage heater with 2 dials
Your storage heater should be directly connected to your off-peak electricity supply. This means it automatically charges up with heat during off-peak times when the electricity is cheaper on a time of use tariff.
The 2 dials on your storage heater will usually be labelled:
‘input’ - or sometimes ‘overnight charge’
‘output’ - or sometimes ‘room temperature’ or ‘boost’
Set the input dial to control how much heat is stored during the off-peak times.
The higher you set this dial:
the more electricity you use
the more heat you store for the next day
Set the output dial to control how much of the heat you’ve stored is released.
Setting how much heat is stored
It’s a good idea to set your storage heater controls before you go to bed.
Set the output dial to the lowest number - this stops heat being used overnight.
The number you set the input dial to depends on how much heat you think you’ll need the next day. Check tomorrow’s weather and think about how much you’ll be at home.
Use these settings as a guide:
| Season | Input setting |
|---|---|
|
Season
Spring |
Input setting
1 to 3 |
|
Season
Summer |
Input setting
1 |
|
Season
Autumn |
Input setting
1 to 3 |
|
Season
Winter |
Input setting
5 or 6 |
Setting how much heat is released
Set the output dial during the day to release the stored heat. Turn it up for more heat and down for less heat.
It doesn’t matter what the input dial is set to during the day - it won’t automatically store heat during peak times.
During the morning and afternoon, try to set the output as low as you find comfortable. The less heat you use during the day, the more you’ll be able to save for the evening.
For example, during colder months you might use the following settings:
| Time of the day | Output setting |
|---|---|
|
Time of the day
Morning |
Output setting
3 |
|
Time of the day
Daytime |
Output setting
2 |
|
Time of the day
When you're not at home |
Output setting
1 |
|
Time of the day
Evening |
Output setting
5 |
If you don’t need heating because the weather’s warm
Turn your storage heater off at the wall.
If you run out of heat
Set the input to a higher number at night. This will store more heat during off-peak times, so you’re less likely to run out the next day.
Some storage heaters have a setting that gives extra heat at any time.
This extra heat uses electricity during peak times. This is more expensive if you have a time of use tariff.
How you control the extra heat depends on the storage heater you have. There might be a separate switch or dial - sometimes called a ‘boost’ control.
In some storage heaters, the extra heat is turned on automatically when the stored heat runs out.
It’s important to know how these settings work on your storage heater. Your electricity bills might be high if you regularly use extra heat.
If you’re not sure how it works, check the user manual or look for instructions online.
Check the instructions
You can find the manuals or guide for your storage heater on the manufacturer’s website.
Some common storage heaters are made by:
Dimplex - find Dimplex manuals on their website
Sunhouse - find Sunhouse manuals on their website
You can also search online for videos showing how to use your model of storage heater.
Using a storage heater with a digital display
Your storage heater should be directly connected to your off-peak electricity supply. This means it automatically charges up with heat during off-peak times when the electricity is cheaper on a time of use tariff.
Modern storage heaters can be set up to automatically decide how much heat to store at off-peak times. They use information about the weather and your usual heating patterns.
Modern storage heaters also have controls to automatically turn your heater on or off during the day.
You can set:
the temperature you want the room to be
the times you want the heater to be on or off
Set the room temperature
Use the dial or buttons to change the thermostat temperature. When the room reaches that temperature, the heater reduces how much heat it gives out.
It won’t always be able to reach the temperature you’ve set if there’s not enough heat left.
You’ll usually find that a temperature between 18°C and 21°C is comfortable. If you have a health condition that could be made worse by the cold, you shouldn’t set your thermostat lower than 21°C.
Set the timer
Your storage heater might have pre-programmed timer settings like:
‘out all day’ - so it only gives out heat in the morning and evening
‘home all day’ - so it heats all day
You can also create your own timer settings.
If you don’t need heating because the weather’s warm
Turn your storage heater off at the wall.
You shouldn’t lose any of your settings - modern storage heaters usually have a battery that backs up your clock and any timers you’ve set.
If you run out of heat
Some storage heaters have a setting that gives extra heat at any time. This extra heat uses electricity during peak times. This is more expensive if you have a time of use tariff.
How you control the extra heat depends on the storage heater you have. It’s sometimes called the ‘boost’ setting.
You might also have an ‘auto boost’ setting that automatically turns on the extra heat when the thermostat drops below the temperature you’ve set. It’s best to turn the auto boost off.
It’s important to know how these settings work on your storage heater. Your electricity bills might be high if you regularly use extra heat.
If you’re not sure how it works, check the user manual or look for instructions online.
Check the instructions
You can find the manuals or guide for your storage heater on the manufacturer’s website.
Some common storage heaters are made by:
Dimplex - find Dimplex manuals on their website
Sunhouse - find Sunhouse manuals on their website
You can also search online for videos showing how to use your model of storage heater.
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.
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.
Page last reviewed on 05 July 2023