Thermostats and controls for electric systems

Electric storage heating and electric immersion heaters for hot water use some different thermostats and controls to systems with radiators, but you can still use those controls to reduce the energy you use and to save money. 

(If your home is heated by a system of water-filled pipes and radiators running from a boiler, you have a ‘wet’ central heating system, not an electric one, whether it is gas, LPG or oil-fired. Find out about thermostats and controls for these systems.)

Controls for electric storage heaters

Controls for electric immersion heaters


Controls for electric storage heaters

Electric storage heaters use  off-peak electricity to ‘charge up’ overnight and then release heat during the day. 

A standard electric storage heater has two controls, an Output setting and an Input setting. The Output setting will control how much heat the heater gives out (as long as there is stored heat available). The Input control determines how much electricity the heater will take from the grid during the coming night, and hence how much stored heat will be available the following day. 

So you need to set the Output dial according to how much heat you want now, and the Input dial according to how much heat you think you will need tomorrow. If a heater runs out of heat in the evening while you still need it, or if the weather gets colder, you may need to turn the Input dial up. If the weather gets warmer, or the heater never runs out of heat in the evening, you can probably save money without getting cold by turning the Input dial down.

Turn the Output dial to zero before you go to bed or go out, so you’re not wasting energy overheating empty rooms. You can probably do this quite early, maybe an hour before you go to bed, as it will take a while for the heater and the room to cool down.

And when summer comes and you don’t need the heaters any more, turn them off at the wall, not just by turning the dials to zero. Remember you will need to turn them on again the day before you need the heating to come back on.


Room thermostats

Just like a central heating room thermostat, this helps to keep your rooms at a comfortable temperature. When the air around the thermostat dips below a set temperature, the storage heaters will release heat until that temperature is reached.

Room thermostats need a free flow of air to sense the temperature, so they must not be blocked by curtains or furniture, or put near heat sources. 

Your room thermostat should be set to the lowest comfortable temperature - typically between 18°C and 21°C. Try turning your thermostat down a degree or two and seeing if you still feel comfortable.


Controls for electric water heaters 


Cylinder thermostat

Your hot water is stored in a cylinder, and the thermostat prevents it being hotter than it needs to be. Once the water has reached the temperature you have set, the immersion heater will turn off. 

Cylinder thermostats are usually fitted between one quarter and one third of the way up the cylinder. They have temperature scales marked: you should set them at between 60ºC and 65ºC. This is high to kill off harmful bacteria in the water, but also hot enough to scald, so mix hot water with cold for safe bathing and washing.  


Time switch

A separate hot water time switch will let you heat the right amount of water at the right time – and take advantage of off-peak Economy 7/10 tariffs. By signing up to one of these tariffs, and setting the timer to heat water at a cheaper, off-peak rate, you will use less electricity and save money.  

Set your water to heat up only when you need it: keeping it constantly hot uses energy. The better insulated your tank, the longer your water will stay hot.


Boost switch 

Most systems have a second, smaller heating element at the top of the immersion cylinder, activated by a boost switch. Use this to heat a small amount of water at expensive peak times during the day.

Work out how much water you use, and how much you could save, in our virtual home.


Insulate first!

You'll always save money on heating if you can make your home better insulated.

And you'll also save money on water heating if you can keep hot water hot – by insulating your tanks, pipes and radiators.