Ads promise small heaters that warm a whole home for a few cents a day. The truth is simple: every electric resistance heater turns electricity into heat equally well. Your heating bill only falls when you change when, how much and with what you heat.
You often see these promises in ads for "energy-saving heaters". This is what they look like when you do the maths.
In January 2023 the UK Advertising Standards Authority (ASA) banned four mini-heater ads as misleading: they implied the heaters would save money and heat a room quickly and efficiently. Read the ASA notice.
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Spot price incl. VAT, in euro cents and euros for every country. On top you pay grid fees and electricity tax, which mostly don't depend on the time of day. Tomorrow's prices will be different. You can only move heating to cheap hours if the heat is stored somewhere: a water heater, the floor, or the building itself before you come home. A heat pump's COP depends on the unit and the outdoor temperature, and is lower in frost.
Four things that work. None of them needs a miracle device.
The spot price changes during the day, often several-fold. A water heater, floor heating and pre-heating before you come home can run in the cheapest hours. This pays off on a spot-price contract.
According to Aalto University, lowering the temperature by one degree cuts heating costs by about five per cent. Heat only the rooms you use, and turn the heat down when nobody is at home or at the cottage.
A heat pump is the only device that gives more heat than the electricity it uses: it moves heat from the outdoor air or the ground. A good unit's COP is typically 3–5, so 1 kWh of electricity gives 3–5 kWh of heat. Less in frost.
Many people don't know what their heating or sauna really costs. When you measure each device, you see what pays off and what doesn't, and "savings promises" are easy to check.
No need to change your electricity company. Starting is free.
Many portable heater manuals forbid using them with an external timer. De'Longhi's manual, for example, says the appliance "must not be powered through an external timer", because the safety system could reset by accident. The danger is a heater switching on by itself while something covers it or stands in front of it. That's why SaveElectro never switches portable heaters on or off. Spot-price control is meant for fixed heaters with their own thermostat, with the relay installed by an electrician. Always read your own heater's manual.
Five things to check in the ad.
Not among resistance heaters. They all turn almost all their electricity into heat, so the same amount of electricity gives the same amount of heat. The only exception is a heat pump, which moves heat from the outdoor air or the ground and typically gives several kilowatt-hours of heat for each kilowatt-hour of electricity.
At full power, 1 kWh an hour. In eight hours that's 8 kWh. The cost is the consumption times your electricity price, plus grid fees and electricity tax. The thermostat switches off now and then, so the real consumption depends on the room and the outdoor temperature.
Not in electricity: the same power for the same time uses the same amount. The difference is in how it feels. A fan heater warms the air near it quickly; an oil-filled radiator gives off heat more slowly and evenly.
We don't recommend it. Many portable heater manuals forbid an external timer, because the heater could switch on by itself while something covers it or stands in front of it. SaveElectro's Price Light can show the price in colour next to a heater, but its Power-when-cheap mode is meant only for things like battery chargers. Spot-price control suits fixed heaters with their own thermostat, with the relay installed by an electrician.
Not directly, because you pay the same price every hour. Then the savings come from the temperature and the way you heat. On a spot-price contract, timing lowers the bill as well. See the next question for how SaveElectro helps on a fixed price.
Even when every hour costs the same, SaveElectro helps you use less electricity:
· Room temperatures: with a room sensor (a Shelly H&T, or a probe on a Shelly Add-on) and a Shelly relay on fixed heaters, such as convectors or floor heating, each room stays between the minimum and maximum you choose, for example cooler bedrooms and unused rooms. One degree lower saves about 5 %.
· What each device costs: a Shelly meter shows what your heating, water heater or sauna costs at your own fixed price.
· A monthly budget: set a limit from your last bill and see every day whether you are on track.
· Alerts: a sauna left on, or a room getting too cold because a heater failed.
· Coming soon: air-to-air heat pumps controlled by room temperature and price through a Sensibo infrared controller.
Fixed heaters are wired by an electrician.
No. With Norgespris you pay the same fixed price every hour, so moving heating to cheap hours doesn't change your bill. A lower temperature, heating only the rooms you use, a heat pump and knowing what each device costs still help. Timing pays off for households that stayed on the spot price.
Finland, Sweden, Norway, Denmark, Estonia, Latvia and Lithuania. It shows today's spot prices in euro cents per kilowatt-hour, including VAT, for every country.
See every day when electricity is cheap, and move your heating to the cheapest hours. The free version needs no payment card.