Oil heaters: Everything you need to know

At its crux, oil heaters work by warming up oil within the device which in turn creates radiant heat for the space. As the oil circulates through the device it passes by a heating element that warms it up before it continues through the heater. This continuous flow allows heat to build exponentially, so while these devices tend to start off slow they heat up quicker over time.

Due to the required flow of the oil, these heaters generally take on similar column-like designs, although you can also get thinner panel heaters that use the same principal.

Oil heaters vary pretty drastically in price, starting from as low as $65 from Kmart, and getting beyond $350 from big brand names like De'Longhi. Most sit somewhere in the middle, with the average price sitting at between $120-$150.

If you're eyeing off one of the cheap oil heaters, you won’t need too much compromise for the lower price. Since the mechanisms on these heaters are all quite similar, the main features you’ll sacrifice with a more affordable option are timers, remote controls, and inbuilt thermostats. These are all great to have, but not entirely necessary if you’re on a budget.

Here are some of the best oil heater deals out there at the moment:

Apart from the obvious benefits that an oil heater can warm up your home, there are some ways where these heaters are better than electric, or gas heaters.

Doesn’t dry out air: Since oil heaters don’t directly apply heat to the air in the room they tend to maintain more comfortable humidity levels. Fan heaters, and even split system air conditioners can burn up the moisture in the air as it is exposed to the heating element, but the radiant heat emitted from oil heaters is much gentler. In our testing we found that a De’Longhi Dragon 4 Pro shifted the humidity by around 13% over a four hour period, whereas the Kmart Fan Heater dropped it by 15% in under 40 minutes. Long exposure to dried out air can result in respiratory issues, dry skin and eyes, throat irritation, and can trigger ongoing conditions such as asthma.

Great heat retention: The oil within the heater holds on to warmth even after the heating element has been switched off, making it much better for heat retention. In theory this means you may be able to actively use the device less while still getting the benefits, but that really depends on your household. Ideally you’ll want to have the oil heater set up in a room with good air circulation, and great insulation in order to get the most out of it.

Low fire risk: As the heating element is entirely encased within the oil heater, these represent a relatively low fire and spark risk. You still shouldn’t dry your socks on it, but if you choose to there is a lower chance of the heater actually setting them alight.

Can take a long time to heat up: Although the oil in the oil heater does present some benefits, it also has some drawbacks. Since the heating mechanism requires the oil to gradually heat up it can take quite some time to feel a real difference in temperature. When we reviewed the De’Longhi Dragon 4 Pro it took over four hours for a small room to lift by 5 degrees celsius. In larger rooms, with high ceilings this run time will only get higher.

Expensive to run: Due to the extended run time, it can actually end up being quite expensive to run an oil heater across the season. These heaters still require electricity to trigger the heating element, so depending on the wattage while in use, you could be looking at around $0.14 - $0.34 per hour to heat your home. Extrapolated out across all of winter, those prices begin to add up.

Benefits from extra airflow: As oil heaters rely on radiant heat they aren’t able to circulate the heat around the room by themselves. If you happen to have good circulation in your home already then this shouldn’t cause much of a problem, but if you don’t then you may need to run a fan to help move the warmed air around. 

Heavy: These big, metal, oil filled devices are very heavy with some getting up to 40kg. This can make them cumbersome to shuffle around the house, even if they are equipped with wheels.

Electricity use is measured in kilowatts or kW, so to determine how much electricity an oil heater is using we need to look at the wattage. At its most basic, a 2400W heater will use 2.4kW of power per hour. However heaters use different wattage on different settings - the lower the setting, the less wattage is being used, and therefore the less electricity as well. 

Since oil heaters come in various sizes, a good indication of how much power one of these heaters needs is the amount of fins or columns it has. Kmart’s 5 Fin Oil Heater uses between 850W - 1000W, while its 11 Fin Oil Heater caps out at 2400W. The wattage also shows us the space this heater can efficiently warm. These capabilities vary depending on room insulation, and ceiling height, but a good rule of thumb is that 1000W (1kW) covers around 9m2.

Similar to the electricity use, the cost of running an oil heater will vary depending on the wattage, setting, and your energy bill charges. According to Australia wide energy price averages in the previous financial year, you’ll pay around $0.14 per hour, per 1000W on your oil heater while it is switched on. If you were to run these heaters for 8 hours a day through all of winter, you’d be looking at an extra $103.04 per 1kW of power. For comparison, an air purifier costs less than $0.01 per hour, and a gas heater can range from $0.25 to over $1 depending on the Megajoule usage.