Storage heater settings for winter: input, output and Economy 7 timing

Quick answer: Input controls how much heat the bricks store overnight on cheap electricity; output controls how fast they release it. Winter baseline: input high, output low until late afternoon, then open up for the evening. Get it backwards and the heat’s gone by lunchtime, and the evening top-up runs at day rates above the 26.32p/kWh single-rate cap.

Storage heaters are the most misunderstood heating in Britain, and the two anonymous dials on top are why. Set them well and an Economy 7 tariff does what it promises. Set them badly and you get a tropical morning, a cold evening and a painful bill. Here’s what the dials actually do.

How a storage heater thinks

Inside the casing is a stack of dense ceramic bricks wrapped around heating elements. During your off-peak window the elements charge the bricks with heat. For the rest of the day the bricks give that heat back, partly through the casing whether you like it or not, and partly through a damper or fan you control. It’s a thermal battery: you fill it at the night rate and spend it during the day. Our Economy 7 and Economy 10 explainer covers the tariff half of the equation.

The two dials, decoded

Input (sometimes “charge”) sets how much heat goes into the bricks overnight. It’s the only dial that costs you money directly. High input, big overnight charge, more cheap heat banked. Low input, small charge. Match it to tomorrow’s weather: high for a cold day, half for a mild one.

Output (sometimes “room temp” or “boost” on the same scale) opens the damper that lets stored heat out faster. It doesn’t create heat and it doesn’t use electricity on older models; it just spends your overnight charge quicker. This is the dial almost everyone gets wrong. Output high all day means the bank is empty by 4pm, exactly when you want it.

Winter settings that work

Two habits matter more than perfect numbers. First, set input the night before based on the forecast, because tonight’s charge is tomorrow’s heat and there’s no topping it up cheaply mid-morning. Second, close the output before bed so the leftover warmth greets you at breakfast instead of heating an empty lounge at 2am.

A worked week makes it concrete. Sunday night, forecast says cold snap: input to 5 on the living room heater, 4 in the hall. Each evening you open the output around 4pm, wind it back at 10. Thursday the forecast turns mild, so Thursday night you drop input to 2. Friday feels warm by lunchtime anyway; output stays shut and the bricks coast into the weekend. Ten seconds of dial-turning a night, and the heater never burns peak-rate units.

If your heaters have a room thermostat and buttons instead of two dials, you’ve got automatic or high-heat-retention models. These measure the room and yesterday’s usage, then charge themselves accordingly, so the advice collapses to: set the target temperature, leave the rest alone. The dial advice here is for the classic two-knob heaters still fitted in most Economy 7 homes.

The boost button warning

Many storage heaters have a boost or convector setting, and some households lean on plug-in electric heaters when the bricks run flat. Both are peak-rate electric heating. On Economy 7, daytime unit rates are usually higher than the 26.32p/kWh single-rate cap figure, which makes a flat-battery evening the most expensive way to heat a room in Britain. If you’re reaching for boost or an oil-filled radiator most evenings, the answer is more input overnight, not more peak-rate top-up. And check your actual off-peak hours on your bill or meter rather than assuming midnight to seven; the window varies by supplier and region.

When the settings aren’t the problem

A storage heater that’s empty by teatime on full input every day is undersized for the room, or the room leaks heat faster than any charge can cover. Newer high-heat-retention models hold their charge far better than the slab-sided originals, and at some point the honest comparison is with a different system entirely. If most evenings still end with a top-up at day rates above the 26.32p/kWh cap figure, that point has arrived. We’ve run the numbers in storage heaters vs heat pumps, and our price cap explainer shows how the tariff rates are set. For a whole-house cost picture, the calculator is the place to start.

FAQs

Why is my storage heater cold by the evening?

Output was open too early, input was too low for the weather, or the heater is too small for the room. Try output closed until late afternoon first; it’s the free fix.

Should I turn storage heaters off in mild weather?

Drop input right down rather than off, and keep output closed. In genuinely warm spells, off is fine. Just remember the room is a day behind your decision: tonight’s setting is tomorrow’s warmth.

Does the output dial use electricity?

On classic storage heaters, no; it releases heat you’ve already paid for. The exception is any setting labelled boost or convector, which draws live, peak-rate electricity. Use it as a last resort, not a routine.