Comparing space heaters and other ways to warm one room

The most effective way to warm one room usually combines a heat source that delivers warmth where people sit with changes that keep the room from losing that heat. A space heater gives fast, local warmth, while thermal curtains, door seals and rugs reduce heat loss and make the heater's job easier. Every option has its own safety rules, and heaters that burn fuel need the most care, so the right choice depends on how long the room needs heat and whether someone is nearby to keep an eye on it.

Electric space heaters

Electric space heaters come in a few styles. Fan-forced ceramic heaters warm the air quickly and are widely available. Convection units warm the air more gently. Radiant units heat nearby objects and people directly, which can feel warm even when the room air is still cool. Fan-forced and radiant heaters can make the spot where you sit feel warm within a few minutes, but neither will warm a large or leaky room quickly on its own. Convection units need longer for the same job.

Running cost is easy to estimate. A heater rated at 1,500 watts that runs at full power for one hour uses 1.5 kilowatt-hours. Multiply the wattage by the hours it runs, divide by 1,000 and then multiply by the price per kilowatt-hour on your electricity bill. A heater that runs all day during a cold week costs far more than one used for a short session in the evening, so it is worth doing the sum before the first long run.

The safety rules are firm. Plug the heater directly into a wall outlet, never into an extension cord or power strip, because the cord can overheat under the heater's load. Keep it at least three feet from curtains, bedding, upholstery, paper and anything else that can burn. Choose a model with an automatic tip-over shutoff and overheat protection, and look for a mark from a recognized testing laboratory on the product. Turn it off when you leave the room or go to sleep.

Oil-filled and panel heaters

Oil-filled radiators hold a sealed reservoir of oil that an electric element heats. They are slow to warm a room but keep giving off heat after the element cycles off, which makes temperatures steadier than a fan heater's on-and-off pattern. Many run quietly and do not stir dust around the room the way a fan heater can, which suits a bedroom or a study. Panel heaters work on a similar principle with flat, slim housings that can sit against a wall.

Both types still get hot on the outside. Keep them clear of furniture, bedding and curtains, and treat their surfaces as hot enough to cause burns. Their cords and plugs follow the same rules as any electric heater, and a heater with a damaged cord should be taken out of service until it is repaired or replaced. Because they warm up slowly, switch them on well before the room needs heat.

Fuel-burning heaters need extra care

Unvented kerosene, propane and gas heaters release the products of combustion directly into the room. Those include carbon monoxide and water vapor, which can build up in a closed space. Many fuel-burning heaters are restricted by local rules or by their manuals, and some are not meant for indoor use at all. Use only the fuel the manufacturer specifies, follow the ventilation instructions exactly, and refuel outdoors after the unit has cooled.

Carbon monoxide is odorless, so an alarm is the only dependable warning. Install a working carbon monoxide alarm on each level of the home and near sleeping areas. If the alarm sounds, get everyone, including pets, outside into fresh air, call emergency services from there, and do not go back inside to shut the heater off. Never use a gas oven, a range or an outdoor grill to heat a room, because those appliances are not designed for it and produce carbon monoxide. Fixed gas wall heaters need professional installation and their own venting, which makes them a separate project from a portable heater.

Insulating the room itself

Thermal curtains reduce heat loss through windows, which often lose heat faster than walls. Close them at dusk, and open the sun-facing ones during the day to let warmth in. Keep curtains clear of radiators, heater intakes and baseboard units, so they do not block the heat or become a fire hazard.

A thick rug helps on a bare floor, especially over tile or concrete that pulls heat out of the feet and the room. A cold floor makes a room feel colder than its air temperature, and a rug adds a layer of insulation underfoot. Door sweeps and draft stoppers reduce the air moving under a door, and weatherstripping on the door edges does the same at the sides. Window film kits can cut draft from a single-pane window, though they do not address heat lost through the wall itself.

Doorways to unused spaces need the same attention. A door that opens onto an unheated hallway, a garage or a room nobody uses lets warm air leak out each time someone passes through, so keep it closed. Where an opening has no door, a heavy curtain hung across it does a similar job.

Moving the heat you already have

Warm air rises and collects near the ceiling. In the heating season, run a ceiling fan clockwise at low speed to bring some of it back down. Furniture placed in front of a baseboard heater or a radiator blocks the heat from reaching the room, so move the chair or sofa back far enough to give the heat a clear path, and keep the door to the room closed so warmth stays in. If a hot-water radiator is cool along the top, trapped air is the likely cause. Bleed it with a radiator key once the system is off and the radiator has cooled, opening the valve until water appears, or ask a heating technician to do it. Steam radiators work differently, so ask a technician rather than bleeding them the same way.

Choosing between them

For short sessions in one spot, a space heater with the safety features described above is the simplest tool, and an oil-filled radiator suits longer, quieter periods. A fuel-burning heater belongs only where electric power is unavailable and the manufacturer and local rules allow indoor use, with the required ventilation and a working carbon monoxide alarm in place. For a room that is cold all the time, the insulating steps usually matter more than the heater, because a heater that runs continuously is a sign that heat is escaping faster than it can be produced.

Measure before deciding. Note how long the room takes to warm, how much of an hour the heater spends running and how the room feels from the seat you use most. If a heater runs nearly all day just to hold a modest temperature, the next step is the windows, doors and walls, which the curtain, rug and sealing advice above is designed to address.