An oil heater is a safe, silent, electric option for bedrooms and closed rooms, while a gas heater gives faster, stronger heat and keeps working through load shedding. Which is cheaper depends on your electricity tariff, your gas price and how you use them, and you can work that out yourself in a minute. Here’s how they compare.
The short answer
- Choose an oil heater for bedrooms, children’s rooms, studies and any room you want to heat overnight or for long periods with the door closed.
- Choose a gas heater for lounges and open-plan areas where you want quick warmth, and for heat during load shedding.
- Many homes use both: an oil heater in the bedroom and a gas heater in the living area.
Side by side
| Oil heater (oil-filled radiator) | Gas heater (portable LPG) | |
|---|---|---|
| Fuel | Electricity | LPG from a cylinder (usually 9 kg) |
| Heat-up time | Slow (it warms the oil first) | Fast, almost instant |
| Heat type | Gentle, even convection and radiant heat | Radiant (panel) or convection (blue flame) |
| Works in load shedding | No (it stays warm for a short while after power goes off) | Yes |
| Safe in bedrooms / overnight | Yes, used as the manual directs | No |
| Ventilation needed | No combustion, so no special ventilation | Yes, always |
| Fumes / CO risk | None from combustion | Yes, if misused or faulty |
| Noise | Silent (may tick as it heats) | Quiet hiss |
| Running cost | Wattage × electricity tariff | Gas consumption × gas price |
| Upfront price band | Entry to mid | Entry to mid (plus a cylinder) |
How an oil heater works
An oil heater is an electric heater, not a fuel burner. An element heats a sealed reservoir of oil inside the fins. The oil never needs topping up; it simply stores and spreads the heat. The fins warm the air around them, which rises and circulates through the room.
Because the oil holds heat, an oil heater:
- takes a while to warm a room, but gives steady, even heat once it’s going;
- stays warm for a while after it switches off or the power cuts;
- has no flame, no fumes and nothing to burn, so it’s the usual choice for bedrooms.
More fins generally mean more surface area and a higher wattage. Models sold locally are commonly in the region of 1,500 W to 2,500 W, with most offering two or three power settings and a thermostat. Brands sold in South Africa include Alva, Defy and Goldair, among others.
Features worth having: an adjustable thermostat, a timer, a tip-over switch and overheat protection. Check the specification, as not every model has all of them.
How a gas heater works
A portable gas heater burns LPG from a cylinder inside its cabinet. Radiant heaters heat people and surfaces directly through ceramic panels; blue flame heaters heat the air. Both give heat within moments of lighting and need no electricity, which is why they’re so popular in South African winters. See our gas heater guide for the types in detail.
The trade-off is that a gas heater burns oxygen and produces combustion gases in the room. That means ventilation, an oxygen depletion sensor (ODS), a carbon monoxide alarm and strict rules: no bedrooms and never while sleeping. Read our gas heater safety guide.
Running costs: do the maths yourself
Tariffs and gas prices differ by municipality, Eskom tariff and dealer, and they change every year. So rather than fixed rand figures, here’s the formula.
Oil heater (electricity)
Cost per hour = heater power in kW × your tariff in rand per kWh
- Convert watts to kW by dividing by 1,000. A 2,000 W heater is 2 kW.
- Find your tariff on your Eskom or municipal bill, or your prepaid vendor’s tariff sheet. If you’re on a block (inclining) tariff, use the rate for the block you usually reach in winter.
- Example: a 2 kW heater on full for one hour uses 2 kWh. Multiply 2 by your tariff.
Reality check: the heater doesn’t draw full power the whole time. Once the room reaches the thermostat setting, the element cycles on and off, so actual use is often lower than the maximum. Running it on a lower setting cuts consumption further.
Gas heater (LPG)
Cost per hour = gas consumption in kg/h × your price per kg
- Find the consumption in the manual (often in g/h; divide by 1,000 for kg/h).
- Price per kg = what you pay for a refill ÷ the cylinder size (e.g. divide a 9 kg refill price by 9).
- If you only know the heater’s kW rating, LPG contains roughly 13 to 14 kWh of energy per kg, so divide the kW by about 13.5 for an approximate kg/h on full.
Comparing them
Work out the cost per hour at the setting you’d actually use, for both. You can also compare cost per kWh of heat: divide your price per kg of gas by roughly 13.5 and set that against your electricity tariff per kWh. Then consider the extras: gas needs a cylinder and you’ll leave a window open, which loses some heat; an oil heater’s cost rises if your winter usage pushes you into a higher tariff block.
Which heater for load shedding?
- Gas heaters work without power, so they’re the simplest way to keep warm during load shedding.
- Oil heaters stop heating when the power goes, though the oil keeps radiating some warmth for a while afterwards.
- Running an oil heater on an inverter or backup battery is usually impractical. A heater drawing 2 kW or more will drain most home batteries quickly and may exceed the inverter’s rating. Check your system’s specifications with your installer before trying.
- A practical approach: heat the bedroom with an oil heater while the power is on (using a timer), and switch to a gas heater in the living area during outages.
For other heating that works off-grid, look at a closed combustion fireplace or a gas fireplace.
Safety notes for both
Oil heaters
- Plug directly into a wall socket, not into an extension lead or multi-plug, unless the manual permits it.
- Keep clear of curtains, bedding and drying clothes.
- Don’t cover the heater.
- Check the cable and plug for damage before each winter.
Gas heaters
- Ventilate, never use while sleeping and keep out of bedrooms.
- Leak test with soapy water at every cylinder change.
- Fit a CO alarm (see smoke and CO detectors).
FAQ
Is an oil heater cheaper to run than a gas heater?
It depends on your electricity tariff, the price you pay for LPG and how you use each heater. Use the formulas above with your own numbers: kW × tariff for the oil heater, and kg/h × price per kg for gas.
Can I leave an oil heater on overnight?
Oil heaters are the usual choice for overnight heating because there’s no flame or fumes. Use one with a thermostat, timer and overheat protection, keep it clear of bedding and follow the manufacturer’s instructions.
Do oil heaters work during load shedding?
No. They need electricity. They’ll stay warm briefly after the power goes off, but they won’t produce new heat until it returns.
Which heats a room faster?
A gas heater. It gives noticeable heat within minutes. An oil heater takes longer to warm up, but gives very even heat once the room is warm.
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