Electric Night Storage Heaters
Electric storage heaters are a less expensive way of using electricity to heat homes than fan heaters, oil filled radiators or radiant electric bar heaters, all of which use on-peak electricity. Storage Heaters use electricity supplied at a cheaper night-time rate (although some tariffs also have a mid-afternoon boost) to store heat in special heat-retaining bricks. These then give out heat slowly and are designed to keep warm for the whole of the following day. You can only get cheap night-time electricity if you are on an off-peak tariff such as Economy 7, Economy 10 or Warmwise, and this may involve adding a second electricity meter if you do not already have one (and paying an additional standing charge). You will need to check this with your electricity supplier.
Modern, slim-line storage heaters often have a charge control (or an automatic charge control) which adjusts the amount of heat stored overnight. An automatic charge control does this by measuring the temperature in the room (or more rarely, outside the house) and if it is milder, stores less heat (saving money in the process). If the storage heater has a manual charge control, you will have to make this adjustment yourself.
Storage heaters give out their heat in two ways:
- by radiation from the front panel - this cannot be turned up or down, so will give out heat continuously, day and night (as long as there are still warm bricks behind it);
- by convected heat in the form of warm air. This can be adjusted simply by flaps above the heat store, which can constrict the airflow through the store, so reducing the amount of heat taken from the store. More sophisticated storage heaters also have a fan which can blow air over the storage area to produce a heat boost; however it will also cool the heater down more quickly and if used too much may result in the storage heater getting cold before the evening when it is able to be heated up again.
Many people like to take advantage of storage heaters for background heat, but find that in the middle of winter they still need to supplement the heating by a direct electric heater, such as a fan heater.
"Wet" Electric Storage Systems with Radiators
A second type of storage system uses off-peak electricity to heat up a large, very well insulated tank of water, typically to 85°C. This is then pumped into a traditional "wet" central heating system with radiators, which can be controlled through a normal controls package (timer, room thermostat and TRVs on radiators). If the temperature in the thermal store falls below 60°C, the water can be kept to temperature using on-peak electricity. This sort of system is typically installed to replace a solid fuel (coal) heating system where homes are off the mains gas grid, avoiding the need for the fuel storage tanks required by oil or LPG systems, or for use in relatively small flats and apartments. Products currently available in the UK include the Gledhill ElectraMate 2000, which uses a smaller integrated unit designed for apartments. In some parts of the country, such as the Channel Islands and Isle of Man, the ACV SmartStore, which uses a larger heat store and separate electric boiler unit, can also be found.
Radiator-based electric systems generally do not need additional room heaters providing the thermal store is properly sized. However in larger homes, they are sometimes used with efficient wood-burning stoves to provide additional spot heating in living rooms. Our sister Logpile website has more information about how to select this sort of stove.
Electric Underfloor Heating
Electric Underfloor Heating works in much the same way as storage heaters, except that there are fewer controls possible. In most cases the electric heating element is laid in the floor at the time the house (or, most often, flat) is built, and concrete is poured around the heating elements to provide the thermal mass instead of the heat retaining bricks. The floor is sometimes then tiled with special heat-spreading tiles. Underfloor heating of this type can be expensive to run. It does not work well with fitted carpets, and can cause wooden furniture to distort. The main advantage of this type of heating is that there are no radiators or storage heaters on any walls.