Storage heaters charge up overnight on a cheap off-peak rate and release the heat through the day. Enter the heater's power rating, how many hours it charges and your night unit rate to see what it costs to run.
Storage heaters only make sense on a time-of-use tariff like Economy 7, where night units are much cheaper than day units. The trade-off is that any electricity you use during the day, including topping up a cold heater, is charged at the expensive day rate. Setting the input and output dampers to match the weather is the main way to control the cost. For how the tariff works see Economy 7 and night rates and storage heaters explained.
Common questions
How much does a storage heater cost to run?
A 3.4kW storage heater charging for 7 hours uses about 24 kWh. On a 16p night rate that is roughly £3.80 a night when fully charged, though you can charge less on milder nights to cut the cost.
Are storage heaters cheap to run?
Only on a cheap off-peak tariff. The night rate makes the stored heat affordable, but they are expensive to run if you top them up at the day rate or are not on an Economy 7 style tariff at all.