Economy 7 Storage Heaters UK: How They Work, Running Costs, Off-Peak Hours and Alternatives

Economy 7 is a long-standing electricity tariff built around cheaper overnight power, and it is closely associated with storage heaters that soak up that cheap electricity at night to release heat during the day. For homes without mains gas, this combination has been a common way to heat the property. This guide explains how Economy 7 and storage heaters work together, the off-peak hours, running costs, the difference between old and modern heaters, and the alternatives available.

How Economy 7 works

Economy 7 is a time-of-use electricity tariff that provides roughly seven hours of cheaper electricity overnight, with a higher unit rate during the day. The name comes from those seven off-peak hours, and the tariff requires a meter that records day and night usage separately.

The idea is to reward customers for shifting electricity use to the night, when overall demand on the network is lower. Households that can move a large part of their consumption, such as heating and hot water, into the cheap window can benefit, while those that use most electricity during the day may pay more overall because the daytime rate is higher than a standard single rate.

Because there are two rates, an Economy 7 bill shows separate day and night consumption. Whether the tariff saves money depends heavily on how much usage can be shifted into the off-peak hours, which is why it suits homes with storage heaters and night-time hot water.

How storage heaters work

Storage heaters use the cheaper overnight electricity to heat internal elements, traditionally bricks, storing the heat and then releasing it gradually through the following day. This matches the Economy 7 tariff, because the heater draws its power during the cheap overnight window and provides warmth when electricity would otherwise be expensive.

Older storage heaters have simple controls, an input setting that governs how much charge they take overnight and an output setting that releases the stored heat. Getting the balance right is important, because too little charge leaves the home cold by evening, while too much wastes heat earlier than needed.

The challenge with traditional storage heaters is that they release heat steadily whether or not it is wanted, so much of the warmth can be lost during the day when the house is empty, leaving less for the evening. This is the main limitation that modern designs aim to address.

Off-peak hours and how to check them

The off-peak period on Economy 7 is typically a seven-hour window overnight, often around 11pm to 6am or midnight to 7am, but the exact timing varies by supplier and region and can differ depending on the meter. Some meters also split the off-peak period rather than providing one continuous block.

Because the hours vary, it is important to confirm the specific off-peak times that apply to a particular property and meter. The supplier can confirm the exact window, and knowing it allows the household to schedule heavy electricity use, such as hot water and appliances, into the cheap period.

Clocks on older meters can drift over time, which can shift the off-peak window away from the intended hours, so it is worth checking that the times are correct. Smart meters can record time-of-use more reliably and may support modern off-peak tariffs that differ from traditional Economy 7.

Running costs compared with gas

Electricity generally costs more per unit than mains gas, so heating a home with electric storage heaters can be more expensive than heating with a gas boiler, even on the cheaper Economy 7 overnight rate. This is why Economy 7 and storage heaters are most common in homes without access to mains gas.

The running cost on Economy 7 depends on the gap between the day and night rates, how much heating demand can be met from the overnight charge, and how well insulated the property is. A well-insulated home that uses most of its electricity off-peak will get more value from the tariff than a poorly insulated one with high daytime use.

Comparing costs means looking at the day and night unit rates and standing charge alongside the household's usage pattern. For homes with gas, a gas boiler is usually cheaper to run, while for off-gas homes the comparison is between different electric heating options and low-carbon alternatives.

Old versus modern storage heaters

Traditional brick-filled storage heaters are simple but inefficient at matching heat to demand, often releasing too much warmth during the day and too little in the evening. They also lack precise controls, which makes them harder to manage and can lead to wasted energy.

Modern high-heat-retention storage heaters, sometimes called dynamic storage heaters, are much better insulated and use fans and electronic controls to hold heat for longer and release it when it is actually needed. They can be programmed with timers and thermostats, giving more control and reducing wasted heat compared with older units.

Upgrading from old to modern storage heaters can improve comfort and reduce waste, although the heaters still run on electricity and the savings depend on usage and tariff. The improved controls make it easier to align charging with the off-peak window and heat release with occupancy.

Alternatives such as heat pumps

For homes looking beyond storage heaters, heat pumps are a low-carbon alternative that extract heat from the air or ground and deliver it efficiently, producing more heat energy than the electricity they consume. Heat pumps work differently from storage heaters and are increasingly promoted as part of the move away from fossil-fuel heating.

Heat pumps require suitable installation and work best in well-insulated homes, and there are government schemes that can support the cost of installing low-carbon heating in some circumstances. Whether a heat pump is suitable depends on the property and its insulation, so an assessment is usually needed.

Other options for off-gas homes can include modern electric heating combined with good insulation and a suitable tariff. The right choice depends on the property, the household's budget and priorities, and the available tariffs, so comparing options carefully is worthwhile before committing to a change.

Frequently Asked Questions

What is Economy 7?

Economy 7 is a time-of-use electricity tariff that provides about seven hours of cheaper electricity overnight, with a higher unit rate during the day. It requires a meter that records day and night usage separately. The tariff rewards shifting electricity use into the cheap overnight window, so it suits homes with storage heaters and night-time hot water, while households that use most of their electricity during the day may pay more overall.

What hours are Economy 7 off-peak?

The off-peak period is typically a seven-hour window overnight, often around 11pm to 6am or midnight to 7am, but the exact timing varies by supplier, region and meter, and some meters split the period rather than providing one continuous block. Because the hours vary, you should confirm the specific times that apply to your property and meter with your supplier, so you can schedule heavy electricity use into the cheap window.

Are storage heaters expensive to run?

Electricity generally costs more per unit than mains gas, so heating with electric storage heaters can be more expensive than a gas boiler, even on the cheaper Economy 7 overnight rate. The running cost depends on the gap between day and night rates, how much heating demand is met from the overnight charge, and how well insulated the home is. This is why Economy 7 and storage heaters are most common in homes without mains gas.

What are the alternatives to storage heaters?

Alternatives include modern high-heat-retention storage heaters with better insulation and controls, and low-carbon options such as heat pumps, which extract heat from the air or ground and can produce more heat energy than the electricity they use. Heat pumps work best in well-insulated homes and may be supported by government schemes in some circumstances. The right choice depends on the property, its insulation, the household's budget and available tariffs.