Updated November 2026.
Every winter, a week or two into the cold, the same calls come in. It trips the board. The plug went brown. It warms the chair but not the room. The bill came and nobody can work out why. A couple of questions later, it's almost never a faulty heater. It's one of a handful of decisions made before it left the shop, or in the first ten minutes at home.
So this is the list we wish everyone read first. Seven room heater buying mistakes we've watched happen, each with its fix and a source wherever there's a number. None of them is about brand, and every one is cheaper to avoid than to put right.
What are the most common room heater buying mistakes?
Running a big heater off an extension board or a small socket, buying one without the ISI mark, choosing the wrong type for the room, buying on wattage alone, skipping the tip-over and overheat cut-outs, putting it too close to curtains or the bed, and forgetting what it costs to run. Those seven cover nearly every heater complaint we hear in a season, and we've put them below in roughly the order of how much harm each can do.
One correction before we start. The older version of this page told you to look for heaters with Energy Star ratings or ones labelled eco friendly, because an efficient model would cut your bills. That advice sent people looking for a label that doesn't exist, and we'd rather fix it than leave it standing. Ontario's Save on Energy programme points out that space heaters aren't certified under ENERGY STAR at all, because any electric heater is 100% efficient at turning electricity into heat (Save on Energy, IESO). What lowers the bill is fewer watts for fewer hours, and we'll come back to that at mistake seven.
Can you plug a room heater into an extension board?
No. Plug it straight into a wall socket that's rated for it, and never into an extension cord, a power strip or a multi plug adapter. That's the US Consumer Product Safety Commission's advice on extension cords and power strips, and it's the first of the room heater buying mistakes we raise when somebody's carrying a heater to the billing desk (CPSC safety alert).
The reason is simple arithmetic. Divide a heater's watts by the 230 volts on an Indian supply and you get the current it pulls. A 2,000 W fan heater pulls about 8.7 amps. A 2,900 W oil-filled radiator pulls about 12.6. The small three pin socket in an Indian room is the 6 amp kind, and 6 amps at 230 volts is only about 1,380 W. A multi plug board adds its own thin cord and crowded contacts on top of that. Anything bigger than a small halogen is asking that chain to carry more than it was made for, for hours at a time.
The CPSC adds two checks for the first week. Make sure the plug fits tightly in the wall socket, and while the heater runs, touch the plug, the cord and the socket plate now and then. If any of them is hot, stop using it and get an electrician to look at the socket (CPSC). Every heater manual we've read on the shop floor says the same thing about extension cords, and it's almost always the reason behind the brown plug people describe to us.
The big radiators need the heavy duty 16 amp socket, the same kind an AC or a geyser runs on. We've written that up properly in our room heater size guide, so we won't repeat it here. If that socket's already feeding a geyser, read our note on running a geyser and a heater at the same time before you plug in both.
Is it legal to sell a room heater without the ISI mark?
No. Room heaters are on the Bureau of Indian Standards list of products under compulsory certification, so every one sold in India should carry the ISI mark against IS 302 (Part 2/Sec 30). They've been on that list under the Electrical Wires, Cables, Appliances and Protection Devices and Accessories (Quality Control) Order since 2003 (BIS compulsory certification list).
People are surprised, because they've seen heaters without the mark for sale. The mark means the design and the factory have been tested against the Indian safety standard and are checked on a schedule. BIS's product manual for room heaters sets out what gets tested, including how hot the heater runs, how much current leaks, whether the insulation holds up and how it behaves when something goes wrong (BIS product manual, IS 302-2-30). The CPSC gives American buyers the same advice: ask whether the heater's safety certified and look for the mark (CPSC).
Where this bites is online, with a cheap heater from a brand you can't find anywhere else. Look for the ISI mark on the heater itself, not just in a listing photograph, with the standard number and a licence number printed beside it. If you buy from us, ask and we'll show you where it's printed on the unit.
Which heater type is the wrong one for your room?
The one whose way of heating doesn't match how long you sit in the room. That's the mistake behind most "this heater doesn't work" conversations we have, and in every case the heater was working exactly as designed.
We won't redo the full comparison of types here, because our guide to the right room heater for home lays out halogen, fan and oil-filled side by side. Here are the mismatches we see most.
| The mistake | What it feels like | What to buy instead |
|---|---|---|
| A halogen to warm a whole drawing room | Warm shins, cold room | An oil-filled radiator sized for the room |
| A fan heater left on all night in a bedroom | Hum, hot air on your face, a dry throat by morning | An oil-filled radiator on a thermostat and a timer |
| A big 13 fin radiator for a study you sit in for an hour | Room's warm just as you leave | A fan heater or a halogen pointed at the chair |
| Any heater in the bathroom, near the tap or the shower | Water and electricity in the same corner | Warm the bathroom from outside the wet area before you run the water, then switch off |
That last row matters most. De'Longhi's radiator manuals tell you not to use the heater in the immediate surroundings of a bath, a shower or a swimming pool, and the CPSC says to keep electric heaters away from water and never touch one when you're wet (De'Longhi radiator manual, CPSC). If you're torn between just the two most common types, our electric heater vs oil-filled heater guide goes through them head to head.
Is a higher wattage room heater always better?
No. Watts tell you the most heat a heater can give, not whether it's right for your room, and the top setting is the one that decides which socket you need. Buying on wattage alone goes wrong in both directions, and we see both every season.
Too small is the obvious one. Too big is the one people don't expect, and it's one of the room heater buying mistakes we see most from careful people. Somebody buys the 2,900 W radiator for a 10 by 12 bedroom because it's the biggest number on the shelf, and it roasts them out. Worse, it needs a 16 amp socket the room doesn't have, which takes them straight back to mistake one.
For sizing, the one line worth remembering is about 10 watts for each square foot of floor, and our guide to room heater sizes works it through room by room. Then look at the steps under the headline number. A radiator with 1,000, 1,500 and 2,500 W settings behaves like a small heater on a mild evening and a big one on the coldest night. A heater with one setting can't.
The older version of this page said an oversized heater wastes energy. With a thermostat, that isn't right. A heater a step up, held back by a thermostat, switches off sooner and doesn't burn more units doing the same job. It's the oversized heater with no thermostat that wastes money.
What happens if a room heater has no tip-over or overheat cut-out?
It keeps heating when it's lying on its face on the carpet or when somebody's thrown a towel over it, which are the two situations that start fires. These are the only two safety features that act on their own when nobody's watching, and they're the two we'd never let a customer go without.
The CPSC estimated that portable electric heaters were involved in about 1,200 fires a year in the United States between 2008 and 2010, and it describes the problem plainly: heaters are high wattage appliances that can ignite curtains, beds, sofas, paper and clothing nearby, and a heater left on unattended can start a major fire (CPSC). That's an American figure and we wouldn't stretch it to Delhi, but the mechanism doesn't change with the country.
- Tip-over switch. Cuts the power the moment the heater falls past an angle. It's what saves the day a child, a dog or a trailing dupatta brings the heater down.
- Overheat cut-out. Shuts the heater down when its own temperature climbs too high, which almost always means something's covering it or blocking the air around it. De'Longhi's manual puts it in capitals: never cover the appliance while it's running, because it can overheat dangerously (De'Longhi).
Here's what we'd add from the counter. Don't take the box's word for it. Ask to see the tip-over switch work, and we're happy to tilt a heater for you before you buy it so you can hear it cut out. Which other safety features are worth paying for is in the size guide we linked above.
How far should a room heater be from curtains and the bed?
At least 3 feet, or 0.9 metres, from the front, the sides and the back, and that goes for beds, sofas, curtains, paper and clothes. That's the CPSC's figure, and it's the one we use (CPSC).
It sounds easy until you measure a Delhi bedroom. Three feet all round means the heater needs a patch of floor about seven feet across with nothing soft in it. In a 10 by 12 room with a double bed and a wardrobe, that often leaves a single spot, and it's rarely the one by the bed where people want it. We'd rule out the corner by the curtains first, because curtains move, and the hem that was a foot away ends up resting on the fins.
Three habits we see that undo the rule completely:
- Drying clothes on the radiator. De'Longhi's manual says never use the radiator to dry garments (De'Longhi). It covers the fins, and it hides the room's real temperature from the thermostat.
- Running the cord under a rug. The CPSC warns this damages the cord and can set it and the rug alight (CPSC). Run it along the wall instead.
- Leaving it on to sleep. The CPSC's advice is never to leave a heater running unattended or while you sleep. Warm the room first and let a timer switch it off.
Why does the cheapest room heater often cost more in the end?
Because you pay the price tag once and the electricity every night, and a heater without a thermostat runs flat out for as long as it's switched on. Two heaters with the same watts cost the same per hour at full power. What separates them is how many hours the element's really on.
The sum's easy. Watts divided by 1,000 gives you the units an hour. At Rs 6.50 a unit, the rate for 401 to 800 units in the Delhi domestic tariff schedule, here's what an hour at full power costs (BSES Delhi tariff schedule).
| Heater on full power | Units an hour | Cost an hour at Rs 6.50 | Four hours a night for 30 nights |
|---|---|---|---|
| 800 W halogen | 0.8 | about Rs 5 | about Rs 620 |
| 2,000 W fan heater | 2.0 | Rs 13 | about Rs 1,560 |
| 2,500 W radiator | 2.5 | about Rs 16 | Rs 1,950 |
| 2,900 W radiator | 2.9 | about Rs 19 | about Rs 2,260 |
Those are the worst case figures, with the element never switching off. Picture two radiators in the same bedroom. One has a thermostat, so once the room's warm it cycles to hold it. The other has heat settings and no thermostat, so it runs at whatever step you pick until you switch it off. The second can be cheaper to buy, and if it's left on through the evening it hands that saving back to the meter. We'd rather you paid a little more once. Of all the room heater buying mistakes on this page, it's the only one that shows up on a bill instead of a plug. Our guide to the right room heater, linked above, works through the monthly units and the tariff slabs heater by heater.
Which room heaters do we suggest to avoid these mistakes?
These two radiators, because each has a real thermostat, a tilt switch and an overheat cut-out, which between them answer most of the room heater buying mistakes above. Both are 2,900 W radiators for a bedroom or a living room with a 16 amp socket. We've given the price band each sits in rather than a number that'll be out of date by the time you read this.
Bajaj Vienna 13 Fins Oil Filled Radiator
The one we suggest when somebody wants a heater that looks after itself. Under Rs 11,000. Bajaj lists 13 wave fins with three heat steps at 1,000, 1,500 and 2,500 W, a 400 W PTC ceramic fan to take the chill off while the oil warms, and an adjustable thermostat. On the safety side it carries what Bajaj calls Quadra Safety Assurance: the thermostat, a manual thermal cut-out, an automatic thermal cut-out and a safety tilt switch. It's ISI approved, with a three year product warranty, castor wheels and a cord winder. Those three steps are why we like it for a 14 by 16 living room, because you'll live on 1,000 or 1,500 most evenings. The older version of this page linked to a Vienna listing that no longer opens. This is the 13 fin Vienna we'd point you to now, and it needs a 16 amp socket.
Philips CX3013 13 Fin Oil Filled Radiator
The one for the person who wants fine control. Under Rs 14,000. Philips gives it 13 M-shaped fins and five heat settings running from 400 W to 2,900 W depending on the mode, on two simple knobs, one for the thermostat and one for the heat mode. The tilt protection switches it off if it leans or falls past 40 degrees, and the overheat protection cuts it when the temperature passes safe limits. Two years of Philips warranty, a carry handle and 360 degree castor wheels. That 400 W bottom setting is what makes it a good bedroom heater for someone who feels the cold but doesn't need a roasting, and it's the setting we point people to first. It needs a 16 amp socket too.
If your socket is the small 6 amp kind and you can't add a bigger one, neither of these is for you. A halogen under about 1,300 W is, and the size guide has one we'd suggest.
What should you check before you buy a room heater online?
Five things: the socket it'll plug into, the ISI mark on the unit, the type for the hours you'll spend in the room, a thermostat and tip-over cut-out on the spec sheet, and a spot three feet clear of anything soft. If an online listing doesn't tell you all five, ask before you pay. You can buy any of the heaters above online from us with delivery across Delhi NCR, and the rest of the range sits in our heaters collection.
Our advice before you spend anything, and it costs us nothing to give it. Go and look at the socket where the heater will stand. If it's the small one, buy a heater under about 1,300 W or get a 16 amp point put in first. Then stand in that spot and look for three feet of clear floor. Most room heater buying mistakes are settled by those two minutes at home, long before anybody looks at a brand. Bring us what you found, or type it into a message, and we'll tell you which heater fits. Quite often it's a smaller and cheaper one than you had in mind.