Heating & Cooling

How Portable Oil Heaters Work Explained (In Simple Terms)

Oil Heater Lg

When looking at portable heaters to keep you and your family warm when the cold starts to roll in, you may be new to space heaters, or perhaps you have never really considered getting an oil-filled space heater. But how do they work? This may fascinate you as they do not use a fan to circulate hot air throughout the room. 

Oil-filled space heaters are just that, space heaters that are filled with oil. However, this oil is very particular. It is called diathermic oil, a special oil specifically made to retain heat for as long as possible.

The heater elements heat up the oil, making a convection current inside the heater itself. As the oil heats up, it will heat the metal casing that holds the inside.

As you continue reading this article, it will cover many possible questions regarding oil-filled heaters. At the end of the article, we will also discuss a few things. These subjects include a few of the highest-rated heaters on Amazon for you to look at so you understand what to look for regarding safety and bonus features.

How Do Portable Oil Heaters Work?

The way an oil-filled heater works is relatively simple. These heaters are made out of a metal casing filled with oil. Alongside the oil, the heater comes with essential utilities to make the heater function, such as buttons and a faceplate. The oil inside the space heater is what makes it function how it does.

Diathermic oil is a particular oil with a very high boiling point and an even higher smoking point. This is the opposite of your typical cooking oils like olive or canola.

While the diathermic oil has a high boiling and smoking point, it retains heat very effectively. This means that once the oil is heated thoroughly, it will contain the heat for a long time, thus continually heating the metal casing enclosed.

As the oil and the enclosure heat up, it creates a convection current in the room you are trying to heat up. A convection current is when any gas or water (in this case, the air in your room) and the heated air rises.

As it cools down, it falls back down where the heater is, thus completing the cycle and restarting it all over as it rises back up. This is essentially how an oil-filled space heater works and warms up the room you place it in.

Do You Have To Refill The Oil In Oil-filled Heaters?

No, you need to replace the oil in your oil-filled space heater.

When the heater is made, the oil is sealed inside the radiator by the manufacturer. This gives the oil no way to refill nor leak out of the heater itself. 

What To Do If Oil Leaks Out

That being said, the oil can leak out if the heater is misused or stored away improperly. Hitting the heater, dropping stuff on it, or putting heavy items on top of it while being kept away can cause the weld to break or chip away.

This can cause the oil to start to leak out of the heater. Once this happens, the heater is no longer able to function and can cause damage to your home if you use the heater while it leaks.

The only way to fix the issue if the heater gets a leak is to see if the heater’s manufacturer’s warranty is still viable. You must go through a return process to ship the heater back to the manufacturer if it is still within the warranty period.

They will then examine the damage and either repair the one you sent or send you a new or refurbished one (depending on the manufacturer). If the warranty has expired, your only option is to dispose of the heater correctly and get a new one if you desire. 

Do Oil Heaters Use A Lot Of Electricity?

No, they do not. They are one of if not the most cost-effective heaters when it comes to heating your home with a minor cost increase to your monthly electricity bill. Diathermic oil is the main contributor to this.

Because the oil is so good at retaining its heat, once the heater’s temperature gauges know that the oil is thoroughly heated, it will stop consuming electricity to heat the oil. It will then reheat the oil again when it starts to cool off.

When the oil is thoroughly heated, the only electricity it uses is a small amount needed to run the controls and keep the heater on. Another bonus from the oil is that the oil will still retain its heat if you turn it off.

Therefore, it will keep the metal enclosure hot, warming the room until the oil cools down enough that the heat is ineffective in keeping the metal warm.

Can You Get Carbon Monoxide Poisoning From An Oil Heater?

Once again, carbon monoxide is only produced by natural gas that is not burning correctly. Most space heaters, including oil-filled radiators, convert electricity into heat in various ways.

The only type of heaters you need to worry about getting carbon monoxide poisoning from are those natural gas heaters, like propane heaters. Even then, those heaters have to have some malfunction for the gas to burn improperly. 

That being said, there are ways around this. There are plenty of signs you can look for if you think your propane heater is producing carbon monoxide.

Also, if you are using a propane heater inside, you should adequately vent the room to let the water vapor and carbon dioxide out, which are both non-toxic and breathed in by us daily.

If you are or plan on using propane heaters, get and install carbon monoxide detectors throughout your home.

Kidde Carbon Monoxide Detector, AC-Plug-In with Battery Backup, CO Alarm with Replacement Alert
$37.99 $24.84
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03/10/2024 05:49 pm GMT

Although you cannot get carbon monoxide from portable oil heaters, it is still essential to go over some signs of carbon monoxide: 

  • Dizziness
  • Dull headache
  • Weakness
  • Confused behavior
  • Blurry vision
  • Nausea or vomiting
  • Shortness of breath
  • Loss of consciousness

How Long Do Oil Filled Heaters Last?

Oil-filled space heaters are among the longest-lasting heaters on the market if properly used and stored. If the proper steps are used when using your heater to keep you comfy and warm, you can expect your oil-filled heater to last 20 years before needing to be replaced. 

Making It Last Long

With that said, if you want to keep your electric oil heater as long as possible, there are a few things you need to keep in mind when using the heater and storing it away.

  • Tip #1: First off, when using the heater, try not to keep it in its highest setting for long periods. This can cause the diathermic oil to deteriorate faster.
  • Tip #2: Along with that, do not keep the heater on for long periods. Most come with an automatic shut-off switch if they are on for 10 or more hours at a time, leaving it off for an hour or waiting for it to cool off before turning it back on.
  • Tip #3: If the heater you own or plan to purchase does not have an automatic shut-off switch, try to give it brakes, and above all else, do not leave your oil space heater on 24 hours a day.

Storing Method

When properly storing the oil-filled heater during spring and summer, please put it in a closet or somewhere else in storage. Wherever you deem fit to keep it will probably be okay. However, please do not put anything on top of it or lean anything against it.

Do your best not to knock it into or anything into the heater. This can cause leaks if the impact is hard enough. You can get away with putting some light objects like blankets on top of it, but nothing too heavy.

When you decide you need the heater again, be careful pulling it out of wherever you choose to store it and give it a good wipe down. Dust can and will gather on the heater as it is being used and stored away.

Heating that dust will cause it to be essentially baked onto the heater’s metal, which can cause the radiator to lose some of its heating effectiveness if the dust gets caked on there enough and even start fires in the right conditions.

You can, however, wrap the heater in a blanket to help reduce the dust build-up, but you should still whip it down before using it after long unused periods.

Night Lg

Can You Leave An Oil Filled Heater On Overnight?

You can leave a lot of heaters on overnight. However, when it comes to oil-filled space heaters, this is one place where they work very effectively. Because oil heaters are a turn-on and forget type of heater and the heater’s oil is non-combustible, oil-filled heaters are the least likely to start fires. 

That said, it would be wise to take steps if you want to keep your heater on overnight. 

  • To start, make sure your space heater is in working order. Take note of dings, dents, or other defects in your power cords. Depending on the type of space heater used, they can cause an electric shock, a burn, or a carbon monoxide gas leak.
  • Keep combustible materials away from space heaters. Maintain a 3-foot or greater radius around your space heater. Stacks of paper, trees, sheets, and bedding should be kept away from the machine.
  • You should keep space heaters away from the bedside. Regardless of how badly you like to curl up in the sun, keep a space heater away from your bunk.
  • Purchase space heaters with overheat and tip-over protection. These safety features can help relieve some of the stress of using a space heater.

    A tip-over or tilt-over switch means the device immediately shuts down if it is flipped over. When the temperature approaches unsafe thresholds, overheat safety senses and shuts down the machine.
  • Connect your space heater to an outlet directly. When working with an electric heater, it is not advisable to use an extension cable.

    The extension’s risks of overheating, causing electrical shock injuries, or causing fires are high and should be stopped. If you use an extension cable, ensure it is properly rated and sized for your space heater.
  • Any floor of your home should have smoke and carbon monoxide detectors fitted.

    Although oil heaters do not produce carbon monoxide, it is important to place these alarms outside of sleeping areas and inside each bedroom to prevent carbon monoxide poisoning. Check to make sure they’re in decent working order daily.

Highly Rated Oil Filled Space Heaters You Can Look Into

This will be a small list of oil-filled space heaters you can look at if you want to purchase one for you and your family. There will be links and descriptions of each of the following.

Our Top Pick
Pelonis Oil-Filled Radiator Heater with Programmable Thermostat
$86.17 $76.89

Pelonis oil-filled radiators are perfect for medium to large-sized rooms and come with a range of safety features to keep you and your loved ones safe. With an automatic overheat protection system, these heaters are perfect for use by elderly people or children.

Buy Now on Amazon
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03/11/2024 04:24 am GMT

The Pelonis oil-filled heater is available in a range of colors to complement the decor of your house.

This heater has several heating configurations for fast and effective heating in the room; it has three different heating modes (High, Low, Eco.)

This heating system has temperature settings that allow you to set your preferred temperature between 65 and 85 degrees Fahrenheit for a total affected area of 164 square feet. 

This oil radiator, intended for medium to large spaces, can offer full and constant heating without using a fan or other noisy sounds that interfere with sleep, work, conversation, or studying.

The PELONIS has many safety features, including an impressive 10-hour timer with remote control, meaning you don’t have to leave your comfortable bed or sofa. It also has built-in overheat security and a tip-over safety switch in case of mishaps or malfunctions with the computer.

Pelonis space heaters are lightweight and portable due to four swivel caster wheels and a robust holding handle. The heater’s cord rewind at the bottom is designed for convenience and storage.

The Pelonis comes with a factory warranty that guarantees the provider will repair the heater at no cost if any problems arise within the first year of purchase.

Safest Space Heater - Top Pick
De'Longhi Full Room Radiant Heater
Buy Now on Amazon Buy Now on Sylvane
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03/11/2024 02:19 am GMT

This heater has one of the quickest room heat-up times, with 25% more space for air circulation and quiet operation. Not only would you be unaware of its presence, but your room would quickly heat up.

This oil-filled space heater has several safety features, including the required tip-over security, aided by its extra-wide feet.

Another safety trait is a thermal cutoff for overheating power, which prevents fires or explosions. It also has an insulated heating system that heats the diathermic oil permanently sealed inside the heater.

The De’Longhi comes with a few exclusive features for your convenience. This involves a 24-hour programmable timer that allows you to set various times for your radiator to turn on during the day and night.

It also has an anti-freeze setting that flips the device on when the temperature falls under 44 degrees Fahrenheit.

Final Thoughts

Now that you have finished reading this whole article and looking at the multiple options it has provided. We hope to have provided you with all the information you were looking for and possibly show you the perfect heater to keep you and your family comfy and warm in the coming months.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.