What's the cheapest way to stay warm? From central heating to electric blankets, hot water bottles and fan heaters, here's what they cost to run

Some parts of Britain could soon see frost for the first time this winter, as temperatures are set to fall from Thursday.For those who haven't yet turned their heating on, this weekend may test their resolve as the mercury is forecast to drop below zero overnight. But with bills having risen for many when the energy price cap was hiked in October, lots of households will be conscious of keeping costs down. The energy price cap, which sets bills for those who aren't on a fixed tariff, increased by 4 per cent on October 1, mainly because of higher oil and gas prices linked to the conflict in the Middle East. The average household that pays by direct debit can now expect to pay around £1,723 for electricity and gas each year, with the cap set to rise again in January. But there are ways to keep warm while also keeping costs down – especially if you know the cheapest appliances to use. We asked energy experts at the comparison website Uswitch to crunch the numbers on popular heating devices and work out the cheapest to run. It compared central heating, a plug-in electric fan heater, an electric blanket and a hot water bottle filled using a kettle. Time to turn the heating on? We look at the costs of different ways to stay warmIts calculations for energy use are calculated in pence per kilowatt hour. The cost for each unit of electric or gas is based on Ofgem's October average electricity rate of 26.32p per kWh, and average gas rate of 7.97p per kWh. Central heating Gas central heating is usually the most cost-effective if you want to heat an entire home. Uswitch calculated that a standard gas boiler and central heating system in an average-sized home uses an average of 4.2kW per hour, and costs about 67p to run for two hours. While 4.2kW per hour is more than any of the electric devices below use, the cost per unit of gas is much cheaper than electricity, meaning that it is not as expensive to use as (for example) an electric fan heater at 2kW. Uswitch's central heating calculations are based on a typical household using 9,500kWh of gas a year, with about 75 per cent of that going on heating, spread across eight hours a day over seven months. Ben Gallizzi, energy expert at Uswitch, said: 'Turning radiators down in rooms you're not using and closing the door can retain the heat where you want it and keep the central heating bill down.'Check the temperature on your thermostat and adjust it if required.'With energy bills high and expected to rocket in January just as the coldest weather bites, the best way to save money is to lock in a decent fixed rate deal and be mindful of your usage.' You can check the best fixed tariffs using This is Money's regularly updated energy deals round-up. If you spend most of your time in one room, heating just the space you are in – or even better, just heating your own body – can be much more cost-effective than switching the heating on.There are a few caveats to this. The NHS recommends that rooms you use regularly are heated to at least 18 degrees in cold weather. And even if you don't use a room often, letting it get very cold for long periods can result in mould and damp issues, especially in older homes. How much do your appliances cost to run? How to work it out Every appliance has a power rating, usually given in watts (W) or kilowatts (kW) and 1,000W equals 1kW.This tells you the amount of electricity it uses - and how much it costs you will depend on how long it's turned on.Electricity is sold by kWh, which tends to come up as 'units' in your bill.You can work out how much an electrical appliance costs to run by multiplying the device's wattage by the number of hours you use it and then by the cost of electricity in kilowatt hours. Ofgem's October average electricity rate is 26.32p per kWh, and its average gas rate is 7.97p per kWh. Electric blanketThere are multiple types of electric blankets on the market. Some are designed to be used in bed and others as a throw on the sofa. They also usually come with distinct temperature levels so you can choose how toasty you get. Most modern models are very cost effective. They use on average 100W of power per hour, according to Uswitch.At typical energy prices, this means they could cost as little as 5p to run for two hours. Ben Gallizzi of Uswitch said: 'The cheapest way to stay warm is heating yourself, not the room. An electric blanket costs as little as 5p an hour, while a hot water bottle is an affordable option, and wearing extra thick layers can help.'Most of the time, it takes around ten to 15 minutes to preheat a blanket and you need to turn it off or unplug it before falling asleep.Some models have built-in safety features but not all. Electric blankets can be bought from shops like Dunelm, Amazon or Argos for around £25 to £100-plus. On the whole, they are the cheapest way to heat just yourself, rather than a whole room. But having more people in your home (and therefore running multiple electric blankets) could lower its cost-effectiveness slightly.Plug-in electric fan heaterPlug-in electric heaters might seem cheaper to run than central heating because they're small and compact. However, thanks to their relatively high power use and the fact electricity is more expensive than gas, the opposite is true. Granted, they provide quick, localised warmth for small rooms.According to Uswitch, an average electric fan heater uses 2kW of power on average per hour and costs £1.05 to run for two hours. If you keep yours on for four to eight hours a day, that's £2.10 to £4.20 a day.Plugging in an electric heater for several hours is likely to be more expensive than turning the heating on. However, if you have a large or draughty home which leaks heat easily, using an electric heater for concentrated warmth in one room – for example by your desk if you are working from home – could be more cost effective. Emma Spencer, energy expert at Compare the Market, said: 'While portable electric heaters use significantly more electricity than alternatives such as electric blankets or heated throws, they can still be a cost-effective choice if you're only looking to heat one room rather than your entire home.'Hot water bottleFor an evening on the sofa, a hot water bottle could be enough to keep you warm and toasty without heating the whole room. Boiling a kettle with one litre of water in it uses 3kW of power on average, according to Uswitch. It takes around 2.5 to 4 minutes to boil a kettle. If you were to boil the kettle for ten minutes total, enough for two or to four hot water bottles, that would cost you just 13p.Buying a good quality hot water bottle makes all the difference too. The best kinds have thick walls, a large capacity and an insulating cover.They typically cost between £3.25 and £42.99, depending on the material and capacity.A hot water bottle typically lasts two to six hours before it gets cold.Emma Spencer says: 'Ultimately, the most cost-effective approach is to match the heating method to your needs. 'If you're staying in one spot for a couple of hours, an electric blanket or hot water bottle could help keep costs down. 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