Which is better oil or oil free heater?

Quick Answers

Both oil and oil-free heaters have advantages and disadvantages. Oil filled heaters provide more even and consistent heat, while oil-free heaters heat up faster and are safer and easier to maintain. Oil heaters are more energy efficient but oil-free models are safer, cleaner and more portable. Overall, for most homes an oil-free heater is recommended due to lower running costs and simpler maintenance.

How Do Oil Filled and Oil-Free Heaters Work?

Oil filled heaters, also known as radiator heaters, work by heating oil stored inside the unit. The oil is warmed by an electric heating element. As the oil heats up it slowly radiates heat into the surrounding space. Oil has a high specific heat capacity meaning it efficiently retains heat. The oil stays warm and continues radiating heat even after the heating element turns off. This allows oil heaters to provide a steady and even output of heat.

Oil-free heaters work by directly heating the air within a room. They pull air over an electric heating element which warms the passing air. This direct heating means they can raise the room temperature quickly. However, when turned off they stop heating instantly. The warm air does not linger like the stored heat of an oil filled heater. Without a thermal mass, oil-free models create more of a quick blast of heat.

How Does an Oil Filled Heater Work?

Inside an oil filled heater is a sealed reservoir filled with a mineral based oil. This oil has a high specific heat capacity and density. When the heater is turned on, the electric heating element heats up this oil. The warmth is absorbed by the thick viscous oil and slowly dispersed through convection currents in the oil.

The warmed oil heats the outer surfaces of the sealed reservoir, turning the entire heater into a radiator. The reservoir is made of metal with many fins to optimize heat transfer into the room. A fan helps move the warm air into the space. The oil provides a constant source of warmth for the radiator surface and fins even after the heating element turns off. This allows an oil heater to provide steady heat with gentle warming cycles.

How Does an Oil-Free Heater Work?

Oil-free heaters use either a ceramic heating element or quartz infrared heating tubes. These heaters blow air directly over the electric heating elements to warm it. The warmed air then blows out into the room through convection. When turned on the heating elements quickly glow red hot. They transfer heat directly into the passing air stream.

Some oil-free heaters use a fan while others rely solely on natural convection currents. Fan heaters actively pull air from the room, heat it, and blow the warmed air back out. Convection heaters rely on rising warm air currents to distribute heat. The heat rises from the top vents while cooler air is drawn in at the bottom. Without a thermal mass, heat is produced only while the heating element is powered on. The room air is warmed but there is no retained heat.

Comparing Efficiency: Oil vs Oil-Free

Oil filled heaters are generally more energy efficient than oil-free models. The oil acts as a heat reservoir absorbing heat from the electric element and slowly radiating it into the room. This means the heating element needs to be turned on less frequently to maintain the set temperature. Oil heaters only need to come on occasionally to warm up the oil back up.

Oil-free heaters must directly heat and reheat room air continuously to maintain a warm room temperature. The heating element must stay on for longer periods of time and cycle on more frequently compared to an oil heater. However, some high end oil free heaters have electronic thermostats to optimize run time and improve efficiency.

Do Oil Heaters Use More Electricity?

No, oil heaters actually use less electricity than comparable electric or oil-free heaters. The oil allows the heater to provide more consistent and even heat with the heating element turning on less frequently. Over an entire room heating season oil heaters consume 10-25% less power. They provide more heat over a longer period from the same amount of electricity.

Do Oil Heaters Cost More to Run?

Oil heaters are cheaper to run than oil-free models. The major cost of any electric heater is the electricity consumption. As oil heaters use less power over the course of a heating season, they have lower operation costs. The actual cost savings depends on heater usage, room size, climate and electricity rates. For the average room, an oil heater costs 1-2 cents per hour less to run.

Heating Ability and Effectiveness

A key advantage of oil filled heaters is their ability to provide consistent, even heat. Once warmed up the oil maintains heat output passively over long periods. Oil heaters can evenly heat and maintain the temperature of a room or space. Oil-free models provide more direct but sporadic heat. They may heat up a room rapidly but not hold it at a stable warm temperature.

Do Oil Heaters Heat Better?

Oil heaters provide more effective heating for maintaining a comfortable ambient room temperature. Oil filled models produce a steady radiant heat that slowly warms the surrounding air and objects. This creates a more stable and uniform warmth through the room. The oil absorbs and emits heat continuously creating consistent heat with gentle warming and cooling cycles.

Do Oil-Free Heaters Heat Quickly?

Yes, oil-free heaters heat up a room far quicker than oil filled models. Without having to warm up a thermal mass, direct fan heaters or fast-acting convection heaters can raise the room temperature rapidly. They blow out hot air immediately once powered on. However, oil-free heaters then cycle on and off frequently to try maintaining the warmer air temperature. This can result in uneven heat and wider temperature swings.

Safety and Hazards

Oil-free heaters are inherently safer than models filled with hot oil. Oil heaters present some risk of fire if the elements overheat or a leak occurs. They also remain hot to touch for some time after being turned off. Oil-free heaters cool down rapidly when powered off. They can also be made safer by using cool-touch materials.

Are Oil Heaters a Fire Hazard?

There is a small risk of fire with oil heaters if used incorrectly. Overheating the elements can burn the oil, producing smoke and raising fire risk. The thermal tip-over switch on modern oil heaters turns them off automatically if knocked over. This prevents fires from spilling hot oil. With proper use oil heaters do not represent a major fire hazard.

Do Oil-Free Heaters Remain Cool?

Yes, a key benefit of oil-free heaters is that they remain cool and safe to touch within a minute or two of being turned off. The outer housing and grilles quickly return to room temperature once the heating element is off and cools down. Oil heaters retain heat in the oil much longer, remaining hot to touch for 30 minutes or more after shut down.

Noise Levels

Oil-free heaters tend to be noisier than oil filled heaters. Fan powered models produce the most noise from the rushing air sound. Some convection heaters can be near silent though cheaper models may make ticking or buzzing sounds from the heating element cycling on and off.

Oil heaters make very little noise – just a quiet hum or none at all. There are no fans blowing air around rapidly. High-end oil heaters have silent running thanks to quality build and noise insulation.

Are Oil Heaters Quiet?

Yes, oil radiator heaters are extremely quiet. The only sound most make is a very soft hum from the heating element. Unlike noisy fan heaters, there is no rushed blowing air noise. Oil heaters require no active air circulation fan due to using radiant heating from the warm oil reservoir.

Do Oil-Free Heaters Make Noise?

Oil-free convection heaters can be near silent running. However, cheaper models often emit buzzing or clicking sounds from the heating element cycling on and off. Fan models are noisier as they rapidly circulate air within the room. The amount of fan noise depends on the power and speed setting. High velocity fans produce more noise.


Oil-free heaters tend to be more portable than oil filled radiator models. Even compact oil heaters are heavy due to the steel case and oil thermal mass. Oil-free heaters are lightweight and quick to move room to room. Compact fan heaters have carry handles making them easy to relocate.

Can Oil Heaters Be Moved Easily?

While oil heaters come in different sizes, even compact models are bulky and heavy to move around. Smaller 7-10 fin oil heaters weigh 15 to 20 pounds. The weight comes from the thick metal outer casing and oil filled inside. Large multi-room oil heaters weigh 30 pounds or more. The bulkiness also makes moving oil heaters between rooms challenging.

Are Oil-Free Heaters Lightweight?

Yes, oil-free heaters are far lighter and easier to pick up and move as needed. Without heavy oil and outer metal casing, portable fan models and convection column heaters weigh just 4 to 8 pounds. Lighter materials like plastic are used for the outer housing rather than steel. Handles on top make lifting and carrying simple for relocating an oil-free heater.

Appearance and Design

Oil heaters are utilitarian in design with a bulky steel case and simple control panel. Oil-free heaters come in a wider range of aesthetically pleasing designs. Compact fan heaters suit modern decor with gloss colors and sleek curves. Ceramic tower heaters also look attractive.

Do Oil Heaters Look Attractive?

Not really. Oil heater design prioritizes functionality over aesthetics. They feature bulky rectangular shapes to hold as much oil and steel surface area as possible. The outer case is simply finished gray or white metal. The only decorative element is perhaps fake wood grain finish on a couple models. Oil heaters look fine in garages or basements but are rather ugly for most living spaces.

Can You Buy Stylish Oil-Free Heaters?

Yes, many oil-free heaters feature much more attractive and modern styling. There are compact fan heaters in appealing glossy color cases and futuristic shapes. Slimline tower models suit modern decor with gloss black, white or silver casings. Ceramic heaters look elegant and can blend into the background in a room. Oil-free models provide much more choice for different designer tastes.

Maintenance and Cleaning

Oil-free heaters generally require less maintenance than models filled with oil. However, cheaper oil-free heaters have filters that require cleaning or replacing. Higher quality oil heaters are sealed and maintenance free for their lifespan. Overall oil-free models need less care but have consumable filters.

Do Oil Heaters Require Maintenance?

Not for higher end modern models. Older oil radiator heaters needed oil replacement after long periods. Modern sealed chamber oil heaters don’t need any maintanence over their lifespan. There are no filters or parts that require cleaning or servicing. Other than occasional dusting, no maintenance is needed for the lifetime of a quality oil heater.

Do Oil-Free Heaters Have Replaceable Filters?

Basic oil-free heaters often have mesh intake filters that trap dust and pet hair over time. These require cleaning every few weeks, especially in dusty homes. Upscale models have washable permanent filters. Cheaper ones use replaceable filters that need changed every 1-2 seasons. So oil-free heaters need more regular filter maintenance.


For heating effectiveness and running costs, oil filled heaters generally provide superior performance and value. Their ability to provide steady and even warmth makes them better for warming an entire room comfortably. Oil heaters consume less electricity over a full heating season as well. However, oil-free heaters have benefits around safety, portability and ease of maintenance. Ultimately in most homes an oil-free heater is a sensible choice despite higher running costs. Their safety and transportability outweighs the performance advantages of an oil filled heater for the majority of buyers.

Oil Heater Oil-Free Heater
Heating Ability More even, consistent heat Faster initial heating
Running Costs More energy efficient Less efficient, higher costs
Safety Hot surface, burn risks Cool exterior, safer
Noise Very quiet operation Can be noisy from fans
Portability Heavy, bulky Lightweight, easy to move
Maintenance No required maintenance May have filters to clean

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