If you're in the process of choosing a heat emitter, you might consider an oil‑filled radiator and wonder how they work. Renowned for their energy‑efficient and portable design, these radiators are a popular choice in many households and offer a number of benefits.
Oil‑filled radiators are a type of electric radiator and typically feature a plug‑in design. While some models can be wall-mounted, they are usually freestanding, making them easy to move from room to room.
Despite being a common appliance, few people know how oil-filled radiators actually work, so we've called in the experts to explain everything you need to know below. If you're curious about how they function, whether the oil needs topping up, or if they're worth the investment, keep reading.
How do oil-filled radiators work?
"Oil-filled radiators work by heating a reservoir of oil sealed inside the unit," explains Nicholas Auckland, Managing Director of Trade Radiators. "The oil is warmed by an electric heating element, and once heated, it circulates within the radiator’s fins. This stores and radiates heat steadily into the room."
Since this type of radiator doesn't blow air, it's quiet and comfortable for continuous use and is suitable for noise-sensitive rooms. According to Nick Duggan, Managing Director of The Radiator Centre, these heaters can stay warm for 30 minutes to over an hour after they’ve stopped drawing electricity, which is why they’re such an efficient choice.
Nicholas Auckland brings 30 years of heating-industry experience, energy-efficiency expertise and oversight of one of the UK’s largest home-heating ranges, making him ideally placed to explain oil-filled radiators.
Nick has over 20 years of experience in central heating and radiators, leading the team at one of the UK's largest independent suppliers.
Are oil-filled radiators any good?
Yes, oil-filled radiators are a good choice for heating small to medium-sized rooms, providing a steady, even warmth.
You can pick one up for around £30, and running costs can be as little as 15p per hour (based on current kWh rates with a 500W model). They’re an excellent way to heat a single room locally without having to turn on your central heating.
Unlike other portable heaters, such as fan heaters and convector heaters, oil-filled radiators are very quiet and are usually safe to leave on overnight, making them a suitable choice for bedrooms if you want an undisturbed night’s sleep.
While these radiators offer many benefits, whether they’re worth it will depend on your heating needs and preferences, explains Nick Duggan.
He says, "They may take longer to warm up, but their efficiency and low maintenance often make up for these drawbacks over time. However, if you need instant heat or have limited space, you might want to consider other options."
Crowned as the best oil-filled radiator in our buying guide, this model can heat spaces up to 15 cubic meters and features handles for easy portability.
Pros and cons of oil-filled radiators
Before you install an oil-filled radiator, it's important to consider both the pros and cons. Here's what Nick Duggan wants you to know:
Pros
- Energy-efficient: As previously mentioned, these radiators retain heat well (even after they’ve been switched off), which helps you save energy.
- Quiet: Ideal for bedrooms and offices, you won’t be disturbed by fans or blowers.
- Consistent heating: Oil-filled radiators don’t create hot or cold spots, so you can enjoy an even, comfortable warmth.
- Hassle-free: Contrary to popular belief, you won’t need to worry about topping them up with oil or carrying out any maintenance.
- Safe and healthy: These radiators often come with safety features like tip-over protection and overheating prevention to give you peace of mind. Since they don’t dry out the air or consume oxygen, they help maintain good air quality too.
- Portable: Oil-filled radiators can warm areas of your home that a conventional heater can’t reach, simply because you can pick it up and move it wherever you need it.
Cons
- Slow to heat up: Compared to other emitters, you may have to wait a little longer for oil-filled radiators to warm up.
- Higher initial cost: While still generally affordable, oil-filled radiators tend to be more expensive than basic space heaters.
- Limited directional heating: You won’t be able to focus the heat in a specific direction.
- Bulkiness: They are often bulkier and heavier than other portable heaters, which might not be ideal for small spaces.
- Hot surface: Something to keep in mind if you have small children or pets – the exterior can become very hot during operation, which could result in burns if touched.
Do you have to refill oil-filled radiators?
This is a question Nick Duggan is asked a lot, but the answer is no – you don’t need to top up an oil-filled radiator with oil.
Nicholas Auckland explains that the oil simply acts as a heat reservoir, allowing the radiator to provide warmth without sudden temperature swings or frequent cycling.
If you don't mind the bulkiness and waiting a little longer for them to heat up, oil-filled radiators can be a great, energy-efficient choice for your home that doesn’t require complicated maintenance. Now that you have all the information about how they work, you can decide whether they’re right for your needs.
To learn more, read our comparison of oil-filled radiators vs. convector heaters, or check out this feature on why one writer uses an oil-filled radiator to stay warm while working from home.
