A plug-in heater or the boiler: which room to heat from Thursday

Plenty of households will look at a fan heater this week and hope it dodges the gas rise. The rise is real. The plug does not cancel it. This page is the hour, the room and the socket. Photographing a traditional meter is a separate job, on the meter page. The first time you fire the boiler since spring is the first-fire check. Neither of those tells you whether a 2 kW heater should run all evening.

If the socket, the plug or the flex is already hot, scorched or smelling of hot plastic, stop here. Unplug. That is an electrician, not a longer session on a lower setting. Open electrical and use the number on the card.

What actually changes on Thursday

On 26 August 2026 Ofgem announced a 4% rise in the energy price cap for 1 October to 31 December 2026. For a typical dual-fuel household on a default tariff paying by Direct Debit, the published annualised figure moves from £1,663 to £1,723 if that level lasted a full year. Around 35% of households, about 11 million, are on a fixed tariff. Their unit rates do not reset with this cap. A fixed deal can still pick up the electricity VAT change below. Check the bill.

The hourly decision uses unit rates, not the £1,723 headline. Ofgem’s consumer tables for the same quarter, averaged across England, Scotland and Wales for Direct Debit, put electricity at 26.32p per kWh and 54.83p a day standing, and gas at 7.97p per kWh and 29.68p a day standing. Electricity in that table is shown with VAT at 0%. Gas includes VAT at 5%. Your region, meter and payment method can differ. Prepayment and standard credit have their own cap levels. Read the unit rate on your statement before you treat 26.32p as your price.

Two official changes sit under those pence. From 1 October 2026 to 31 March 2027, qualifying domestic electricity in Great Britain is charged at 0% VAT. That is the temporary zero rate in HMRC’s brief of 8 September 2026. Northern Ireland electricity stays on the reduced rate. Gas stays at 5% VAT. Ofgem says most of this quarter’s cap rise is gas — about 8% on gas bills — and that an electricity-only household sees a much smaller move, under 1%. A plug-in heater burns the electricity unit. A mains-gas boiler burns the gas unit. The standing charge is paid either way, heater on or boiler off, so leave it out of the hourly sum.

What one hour costs on the average rate

A portable electric heater turns the electricity it draws into heat. The Energy Saving Trust treats that as secondary heating: useful when you want one room for a little while, and expensive when it becomes the way you heat the house, because electricity costs more per unit than gas or oil. The wattage on the nameplate is the figure to multiply. A heater marked 2 kW draws 2 kWh in an hour if it runs flat out. At 26.32p per kWh that hour is 52.64p. The same arithmetic, on the same average, for other ratings you will see on the box:

Those rows are 26.32 multiplied by the kWh, rounded to the nearest tenth of a penny. They are the Ofgem Direct Debit average for this quarter, with electricity VAT at 0%. They are not your invoice. A heater that cycles on a thermostat will use less than the nameplate. It will not slip onto the gas price by being small.

Four hours of a 2 kW fan, still flat out, is 8 kWh. At 26.32p that is £2.11. Two such fans, in two rooms, are about £1.05 an hour together before either of them cycles. A heater marked around 3 kW is about the full load of a standard 13 amp plug. It belongs in a wall socket on its own, which is the next section, not a reason to call it efficient.

One kWh of electricity at 26.32p costs a little over three times one kWh of gas at 7.97p, because 26.32 divided by 7.97 is about 3.3. A gas boiler does not turn every unit of gas into heat in the room. This page will not invent an efficiency percentage for your model. The gap between the two published unit rates is still wide: the same amount of heat usually costs less from mains gas than from a plug-in heater. What changes the choice is how many rooms you would otherwise warm, and for how long.

The boiler heats water that can travel to every open radiator. You are not buying one chair’s worth of warmth at 7.97p. If several rooms are in use, or someone is home all day, central heating with the empty rooms turned down is usually the practical choice. If one person sits in one room for an hour or two, a lower-powered heater can burn fewer units than bringing the whole circuit up from cold. A fan left on through the evening because “it is only one room” is the case that overtakes that saving. Do the sum with the wattage on your heater and the unit rate on your bill.

Heating oil sits outside this cap. If the tank in the garden feeds the boiler, the pence on this page do not describe your fill. Read the gauge on the oil-tank page before you order. A heat pump is a different machine from a fan heater. The autumn survey page is the walk-through for that. The flow-temperature page is the radiator dial on a condensing combi, not a plug.

Which room, and for how long

Match the appliance to the evening you are actually about to spend. A short spell in one room and a cold house full of people are different jobs.

Use the plug-in heater when one room is occupied, the others can stay cooler, you can stay near it, and the lead reaches a wall socket without a reel. Switch it off when you leave the room. Use the heating system when more than one room needs to be comfortable, when a child or an older person is in the house for the day, or when you would otherwise run two heaters. Someone who is home all day should have a room that stays warm without a portable appliance left to itself.

If the house is already cold through and you are about to live in it for the evening, bring the system up and turn down the rooms you are not using. Thermostatic radiator valves on empty rooms do that. The first-fire page is the sequence for the programmer, the pressure gauge and one cold panel. Running a fan in the hallway while the boiler is locked out only hides the fault until the socket complains.

A portable heater is a poor repair for a radiator that stays cold every night. One panel cold at the top, with the rest of the house warm, is the bleed guide. Every radiator lukewarm, or a boiler that will not fire, is the will-not-fire check, then plumbing and heating. Buy the fan only as a bridge for a day or two while that visit is booked, and keep the socket rules below.

Tenants should read the agreement before they add heaters the landlord has not discussed. Many leases put the heating system on the landlord. Tell them which room is cold and since when. Leave the boiler case shut.

The socket, before the hour

Electrical Safety First publishes the household rules for portable heaters. The checks here are the ones you can do without taking a socket apart. They are the stop line for this page.

1. Read the wattage on the heater. Near 2 kW or 3 kW, that plug should be the only thing in the socket. A cube adaptor shared with a kettle, a charger and the heater is how a faceplate heats up.
2. Plug into a wall socket. Do not run the heater from an extension lead or a cable reel. Those leads overload easily, and a heater is a common way they do it.
3. Use a heater with a UK 3-pin plug. Skip a second-hand unit, and skip one that arrives with a foreign plug and a travel adaptor.
4. Stand it on a level floor, at least one metre from curtains, bedding, furniture and paper. Keep the front of a fan clear of fluff. Do not dry washing on it or over it.
5. Stay in the house and in reach of it. Do not leave it running when you go out or when you go to sleep. If you want the bedroom warm at lights-out, heat the room, then switch the heater off. An oil-filled radiator holds some warmth after that. A fan does not.
6. After about ten minutes, feel the plug and the socket face. A little warmth can be normal on a high load. Hot plastic, brown marks, a smell, or a buzzing socket means you unplug and stop.
7. If the RCD or a breaker opens, leave it open. Resetting it three times to finish a film is how a fault becomes a burnt socket. Unplug the heater before you try a single reset, and stop if it opens again.

A plug-in heater does not need a building notice. A new circuit, or a fixed heater wired into the wall, can. In England that often falls under Part P. The Part P note explains notification. It does not file anything for you. Scotland uses its own building standards. Ask the electrician what certificate applies there. A listing that shows NICEIC or NAPIT is showing a field that is present. It is not a badge this site sells.

When to unplug and who to call

Stop the homeowner sequence if any of these are true. They are calls, not another hour on a lower dial.

• The plug, the socket or the flex is hot, scorched or smelling. Unplug if you can do it safely, and book an electrician for that circuit.
• The consumer unit trips when the heater is the thing you just plugged in, and it trips again after one reset with everything else out of that socket.
• You can smell burning and you cannot see a harmless cause. If there is smoke, leave and call 999.
• You smell gas while you are deciding whether to fire the boiler instead. Leave the house, avoid electrical switches, and call the Gas Emergency Service on 0800 111 999.
• The carbon monoxide alarm sounds. Leave. The alarm page is the test you do before a planned fire, not the response when it is already sounding.

A warm room and a tired boiler are not, by themselves, an emergency. If the system will not fire when you do need the house warm, use the will-not-fire checks, then a plumbing list. If one socket has become the way the house stays habitable, you want two trades: an electrician for the circuit you have been loading, and a heating engineer for the system you have been avoiding. This site does not email either of them.

Gas work done as a business is for someone on the Gas Safe Register. Ask to see the card and the work types on the back. Owner-occupiers do not get a landlord gas safety certificate by law. An overdue service is still worth booking before the first cold week, when diaries fill. That visit is separate from tonight’s choice of heater.

What to say, and what this page will not do

On an electrical call, say which room and which socket, the wattage on the heater, whether the faceplate is discoloured, and whether a breaker opened. Ask whether the person coming covers domestic electrical work, and whether a repaired socket or a new circuit would need a certificate. For a hot socket, start with the electrical list — for example electrical in London or electrical in Manchester — and use the number on the card.

On a heating call, say you have been using a plug-in heater because a room or the circuit will not heat, and for how many evenings. Have the boiler make and model, any fault code, and whether you are a tenant. Ask whether the person coming is Gas Safe for the work you described, and whether the first figure is plus VAT. City lists such as plumbing in London are the same idea: you place the call.

This page does not switch your tariff and does not tell you a fixed deal is cheaper. Ofgem’s own note says some fixed tariffs sit below the October cap, and that anyone struggling with a bill should speak to the supplier first. That conversation is with the supplier. The meter page is only the reading, if you still have a traditional meter and have not sent one. The cost notes are for a repair in pounds, not for 52.6p an hour. The grant notes are for a scheme such as the Boiler Upgrade Scheme, not for a fan from a shop.

The contact-details page shows how to reach a business yourself. Nobody here forwards the job.