My Cart Resources

Become an Appliance Expert. Subscribe to our Knowledge Base!

The Reason Oil Filled Space Heaters are So Energy Efficient

The Reason Oil Filled Space Heaters are So Energy Efficient

Space heaters are one of the best ways to heat up a room and stay warm. They're also a great way to cut down on your utility costs when energy prices spike in winter. If you find yourself running your furnace harder and longer than you'd like, the best solution may be an oil filled space heater. Oil filled space heaters are energy efficient. They're portable design not only provide you with the flexibility required to concentrate extra heat precisely where you need it, but their unique thermal properties make them a more reliable and efficiency choice than ordinary water, gas, or infrared heaters.

How Oil Filled Space Heaters Work

Despite their name, oil filled space heaters run on electricity, not oil. The oil acts as a heat reservoir, storing and releasing energy over time. When you plug the heater into an electrical outlet, the electricity activates an electric resistor inside the unit that begins converting power into heat, but instead of being released out into the air, the way an ordinary heater would, the heat is absorbed by the diathermic oil in the heater panel or radiator fins.

As the oil heats up, it begins to circulate through channels built into the panel and radiator fins, slowly transferring its heat to the metal, which transfers the heat out into the  room through the process of natural convection. The air surrounding the heater absorbs the heat from the oil filled heater and rises, drawing in cool air that gets heated in turn. The process continues until the entire room reaches the uniform temperature you're most comfortable with. The larger the panel, or the greater number of fins in the heater, the more air is in contact with the heater and the faster the room warms up. Check out the NewAir AH-400 Oil Filled Space Heater or the NewAir AH-450B Oil-Filled Space Heater to see examples of each design.

Why Oil Filled Space Heater Are Energy Efficient

The Reason Oil Filled Space Heaters are So Energy Efficient

NewAir AH-450B Oil-Filled Space Heater

The biggest advantage of an oil filled space heater is their portability, which allows you to provide supplemental heat to the parts of your house your furnace can't reach. One of the downsides of central heating systems is the difficulty of maintaining an even temperature throughout your home. As the day progresses, and the sun shifts and different rooms heat up at different rates. At night, drafts can let in cool air and windows can let out heat, creating a thermal drain that leaves some rooms chronically under heated.

Though it's possible to compensate for these problems by adjusting the furnace thermostat, it's far more efficient to use an oil filled space heater instead. Units like the NewAir AH-400 and NewAir AH-450B both come with carrying handles that allow you to pick them up and transport them safely from room to room, so the heat remains where it's needed most. Some, like the NewAir AH-450B, are even mounted on caster wheels, so they're even easier to move. Because their energy requirements are so much lower than the average furnace (400W - 1500W on average) they provide you a low-cost way of raising the temperature without significantly affecting your energy costs.

Oil filled space heaters are also over 99 percent energy efficient. Unlike gas heaters, which burn propane or natural gas, practically all the electricity consumed by an oil filled space heater is converted directly into heat. A small amount is diverted to run the heater's circuitry and extra features - which may include a thermostat, timer, and adjustable heating modes - but this typically accounts for less than one percent of the heater's energy needs.

But it's the unique thermal properties of the oil inside the space heater that really responsible for it energy efficiency. The diathermic oil that's used inside has a large thermal mass and a high specific heat capacity, which is the amount of heat a substance can absorb before its temperature rises. This allows oil filled spacer heaters to absorb and store a tremendous amount of heat as  it's generated by the electric resistor and release it gradually over time. This not only distributes heat smoothly and evenly throughout rooms they're used in, but it also means the heater continues radiating heat long after the resistor's been switched off. Typically, space heaters have to continuously reactivate its circuitry whenever the heat drops too low. Not oil filled heaters. Their circuitry needs to be reactivated far less often, and the less often its activated, the more efficient your heater will be.

Compared Water Filled Space Heaters

Oil filled space heaters are often compared to water filled space heaters, due to the similar way they produce and distribute heat. Water filled heaters are filled with water, stored in radiator fins, similar to the NewAir AH-450B Space Heater. When the heater is activated, a resistor begins converting electricity into heat. The heat is absorbed by the water, which circulates through


NewAir AH-400 Oil Filled Heater

channels in the fins and heats the metal, which in turn warms the air, same as in an oil-filled space heater. Some water filled space heaters can be connected directly to your home plumbing system, so you can pump in hot water from your broiler or hot water heater instead of relying on a resistor.

Water filled space heaters are declining in popularity due to the comparative advantages of oil filled space heaters, specifically the high boiling point of diathermic oil versus the relatively low boiling point of water. When a water filled space heater warms up, the water inside is typically heated close to boiling (160°-180°F), increasing the vapor pressure on the heater structure. The boiling point of diathermic oil is three times higher than water, so it can absorb more heat without subjecting the unit to the same amount of internal pressure. This allows oil filled space heaters to be lightweight and portable. The lower boiling point of water forces water filled heaters to function as high pressure vessels, so they're heavier and less mobile. Most water filled heaters are actually fixed units, confined to a single room.

How You Know You Need an Oil Filled Space Heater

If you don't know whether your home needs a NewAir oil filled space heater, take a moment to walk through your house and see how evenly your furnace heats the rooms. If you notice any significant temperature drops from one room to another, an oil filled space heater is the best solution. They're the most energy efficient way to compensate for heat loss due to drafts, windows, or poor insulation. 

If you're really interested in saving money on your heating bill, turn down your thermostat a few degrees, just to the point where you'd need a sweater to stay warm, then take your oil filled heater and using it to raise the temperature in the rooms your using. If you own a large house, you'd be surprised by the savings you can accrue by focusing your heat instead of spreading it out. In fact, if the cost to heat a few rooms is less than half the cost to heat your whole house, you're actually losing money by not using an oil-filled space heater to supplement your central heating system.

Downside of Oil Filled Space Heaters

Diathermic oil is the reason oil filled space heaters can continue radiating heat 2-4 times longer than water, gas, or infrared heaters, but it's also the reason why it takes oil filled space heaters 2-4 times to warm up and begin heating as well. Because of its greater thermal mass, there's a noticeable lag between when you turn the heater on and when you start feeling its effects. If you need a heater that can warm you up right away, an oil filled space heater may not be the right choice for you.

Final Thoughts

Oil filled space heaters are the ideal heating solution for homeowners concerned about their energy costs. They're portable and highly efficient, expending relatively little energy, but capable of heating almost every room in your home.

Like our article? Subscribe for more!