Are Oil Filled Heaters Energy-Efficient?

Space heaters are a great way to supplement the central heating system in your home or office. There are about three main types of space heaters: electric, oil-filled and radiant. All three come with their own share of pros and cons, but if you are looking to save costs and conserve energy, we suggest you opt for an oil-filled space heater.

For starters, oil-filled space heaters are easy on the utility bill. Plus, they are much more powerful than their space heating counterparts and can warm up medium-sized to large rooms easily.

Unlike the radiant space heater that emits heat within a focused area in the room or the traditional convection current heater that directly throws out heat into the air, oil-filled heaters work in a more sustainable fashion. These types of heaters warm up the oil present inside the device, which slowly disseminates heat throughout the room. It is due to this slow dissipation of heat that the oil-filled heater is able to create a stable, even temperature for a long period of time.

Oil Filled Radiator Heater Electric Bill

 Heat outputEfficiency ratingCost per hr (mains gas)Cost per hr (LPG*)Cost per unit heat (mains gas)Cost per unit heat (LPG*)
Radiant gas fire (on full)5kW63-81%25-32p41-54p5-6p8-10p
Radiant gas fire (on low)1kW40-65%6-10p10-17p6-10p10-17p
Gas convector heater (on full)3kW60-85%14-20p23-33p5-7p8-12p
Open decorative gas fire2.5kW20-50%20-50p33-84p8-20p13-33p
Closed gas fire4kW60-80%20-27p33-45p5-6p8-10p
Bottled gas fire4kW100%*n/a66pn/a17p

If you are thinking of purchasing a space heater, we suggest buying the oil-filled one. Its thermal properties coupled with its portable nature make it a reliable form of space heating device. But that’s not all. Oil-filled heaters are also highly efficient users of energy and can help you save up on that hard-earned cash. Keep reading for more information.

How Energy-Efficient are Oil Filled Radiators?

How Do Oil-Filled Space Heaters Work?

Before we get to making claims about the oil-filled heater’s sustainable impact, let’s get a grip on how these space heaters work.

An oil-filled heater is made of a series of radiator fins that are stacked together to form a panel. These fins are filled with a special type of oil called diathermic oil and are connected to an electrical resistor. Electric currents run through this resistor when the heater is plugged to a power source. The resistors then begin converting the electric energy into thermal energy.

The key component here is the diathermic oil, which absorbs all the heat generated by the device. The oil starts to circulate in the vessels of the radiator fins and transfers thermal energy to the space heater’s exterior, which is usually made of metal. As the air near the heater warms up, it rises, leaving the cool air to be heated. The entire process is basically a convection current that allows the oil-filled space heater to distribute hot air equally across the room.

What Makes Oil Heaters Energy-Efficient?

They Are Flexible and Portable

One of the biggest drawbacks of using a central heating system is that its heat output is dependent on the average temperature of the air funneled into it via the central heating ducts. As a result, it is difficult to maintain an even temperature with these heaters because all the air in your home or office does not always make it through the duct. Several confounding factors like insulation levels, sun exposure and gapped windows mean that cool air remains trapped in certain spaces.

Luckily, you do not have to encounter this problem with oil-filled space heaters. These heaters are portable and flexible. They can be moved from one room to another so that you can concentrate heating in a particular area of the room. Most contemporary oil heater models even come with handle-based designs so that they can be easily transported to different regions of the house without the user getting skin burns. Some models may also have wheels attached to them so that you can drive them around and really focus the heating where you need it.

They Convert Electrical Energy into Thermal Energy

Oil-filled heaters draw comparatively less power than traditional furnace heaters. Also, because of how they produce heat, almost all of the electrical energy they consume is converted into thermal energy. That is about 99 percent of energy being used on heating. The rest of the one percent is used to operate the radiator fin panel. That’s a good use of oil as fuel.

When speaking of energy efficiency, perhaps the key input here comes from the diathermic oil fuel that has a high heat capacity. Think of the oil as a reservoir of heat energy. Due to its unique chemical properties, it needs to absorb heat for long periods of time before its own temperature rises by one degree. Hence, when the oil gets warmed up, it retains its temperature. In other words, your oil-filled heater is going to be able to emit heat long after you have shut it down. This way, you can save up on the cost of bills because the electricity-consuming resistors positioned inside the heaters will not need to stay active too frequently, giving you a long-lasting cozy atmosphere.


Oil-filled space heaters qualify as superior heating devices when they are paired with the central heating system of your home or office. Yes, they are on the expensive side, but we think you should still go ahead and invest in them since they will help you break even on the costs in very little time.

One way to make a decision is to assess the heating capacity of your central heating system. Naturally, the system will not be able to warm up every room at the same temperature. If you can figure out a lower thermostat for the system that is relatively comfortable, all you need to do is get an oil-filled heater to ramp up the heat in specific regions.

The main benefit of using an oil-filled heater is that it is going to be able to radiate heat three to four times longer than other heaters will, even after you have cut down the power. Thus, if energy efficiency is what you are looking for, the oil-filled space heater is the way to go.

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