Storage heaters divide opinion, and most of that comes down to how they are run rather than the heaters themselves. Feed them the right tariff and set the controls properly and they give cheap, even warmth right through a winter. Run them badly, which is very common, and you end up paying peak rates for heat that has all leaked away by the time the evening turns cold. This guide is about staying on the right side of that line.
How a storage heater works
Inside the case sits a stack of dense ceramic or clay bricks, wrapped in insulation, with electric heating elements buried among them. Overnight, when electricity is cheaper, the elements warm those bricks to a high temperature and the insulation holds the heat in. Through the following day the bricks release that warmth slowly into the room. Nothing burns, there is no flue, and the appliance is really a battery for heat rather than for fuel. That one idea, charge cheaply at night and discharge slowly through the day, drives everything about how a storage heater should be run and explains every way they go wrong.
Why they only pay off on a night tariff
The whole economic case rests on cheap overnight electricity. A storage heater charges during the off-peak window of a two-rate tariff such as Economy 7 or Economy 10, paying the low night unit rate for the energy it banks. Put the same heater on a single flat rate and it charges at full price, losing its entire reason to exist; at that point an ordinary panel or convector heater would warm the room on demand for the same money and waste nothing storing it. So the first question to ask of any storage heater is what tariff is feeding it. The mechanics of those off-peak deals are set out in the Economy 7 and night rates guide, and because the meter has to be able to tell night from day, the smart meters guide is worth reading alongside it.
The two dials: input and output
Older storage heaters carry two controls, and most of the trouble traces back to muddling them up. Input, sometimes labelled charge, decides how much heat the bricks take on overnight; turn it up ahead of a cold snap and down again in milder weather. Output, sometimes labelled boost or room temperature, works a flap that lets the stored heat escape during the day. The classic error is leaving output wide open first thing in the morning, so the heater pours out its warmth by lunchtime and has nothing left for the cold evening when you actually want it. Keep output low or shut while the house is empty, then open it up once you are home. A useful way to hold the two apart in your head: input is how much you charge, output is how fast you spend it.
Setting them through the week
Storage heaters reward a bit of forward thinking, because they respond to last night's setting rather than this minute's. Watch the forecast and lift the input the evening before a cold day, then drop it back when a milder spell arrives, so you are not banking a full charge the bricks will never need. That lag is the awkward part: a sudden mild day after you charged for frost leaves you with surplus heat and no way to claw the money back, while an unexpected cold snap catches the bricks half full. Over a week the pattern tends to settle, with the heaters in the rooms you live in set higher and those in halls and spare rooms kept low. If your weekend at home looks different from your working week, adjust the input to match, since there is no point charging a study heater for a Saturday you will spend in the kitchen.
Old bricks versus modern retention models
Not all storage heaters are the same vintage. The old manual sort, with nothing but an input and an output dial, leak heat steadily whether you want it or not, which is why so many flats heated this way are too warm at breakfast and chilly by nine in the evening. Newer high heat retention models are better insulated, hold their charge for longer, and add a fan, a proper room thermostat and a programmer, so they release heat closer to when you ask for it rather than dribbling it away all day. If you are stuck with ancient units and the bills are high, replacing them with modern retention models can sharpen the control considerably, though the heat still costs the same per unit; the gain is in waste avoided, not in cheaper electricity.
What they cost to charge
A storage heater is rated by how much energy it can bank, often quoted in kilowatt-hours. Suppose a heater stores 6 kWh in a full overnight charge. At an example off-peak rate of 12p per kWh that is about 72p to fill it, whereas the same 6 kWh charged at an example daytime rate of 30p would cost 1.80, so the night rate is plainly doing the heavy lifting. You can put your own heaters through the running cost calculator by entering the heater's wattage and the number of hours it charges overnight. The figure to keep an eye on is any daytime boost: that top-up is drawn at the expensive peak rate, so a heater that has run dry and gets boosted every evening can quietly cancel out the saving the off-peak charge was supposed to deliver. A couple of well-set heaters that rarely need boosting will always beat a houseful of badly set ones leaning on the boost button.
When something else makes more sense
Storage heaters earn their keep in homes off the gas grid, in many flats, and anywhere a night tariff is already in place. If your home has mains gas, a gas central heating system is usually cheaper to run than electric storage heat, so the comparison is worth doing before you spend on replacement units. A heat pump is another route for an all-electric home, turning each unit of electricity into several units of heat, though it is a far larger project. And if you rent and the storage heaters came with the flat, the realistic aim is to run the ones you have well rather than to replace them, which is covered in the saving energy when renting guide. Whatever the setup, the principle holds: these heaters only ever make sense paired with a cheap night rate, and they only ever feel good when the output is held back until you are there to enjoy it.