DeLonghi TRD40615E Dragon 4 Oil filled radiator review

If you're looking to efficiently heat a larger room, DeLonghi's Dragon 4 oil filled radiator takes some beating

T3 Platinum Award
DeLonghi TRD40615E Dragon 4 oil filled radiator
(Image credit: Future)
T3 Verdict

The DeLonghi Dragon 4 is a top choice for those looking to heat a larger room efficiently. It has a comprehensive range of functions and the chimney design is both stylish and helps speed up the heating process.

Reasons to buy
  • +

    Stylish design

  • +

    Fast and efficient heating

  • +

    Silent operation

Reasons to avoid
  • -

    Quite a large unit

  • -

    No remote or app control

Why you can trust T3 Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Reviewing the DeLonghi TRD40615E Dragon 4 was no tough task. I hate being cold and sitting through a long Chicago winter in an old drafty house often left me with ice-cold fingers and toes. The best heaters are perfect for supplementing your regular home heating or providing a localized heat source. 

As someone that works from home, I don't want to heat the whole house when I'm only in one room, so using an electric heater is ideal. I tried various heaters before this one but none that really did the job. I loved the look of the Vornado Glide but it just didn't have the staying power to stave off that sub-zero chill from my window and the sound of many of the tower units was too distracting. 

Oil-filled radiator heaters are non-directional in their heat, which means you don't feel their benefit instantly but they soon fill the room. And from an energy point of view, the fact that they stay hot, even when the power clicks off, means that they are far more efficient. 

The DeLonghi Dragon 4 isn't just any oil-filled radiator though. It has a unique design to make the heating more efficient and the larger build means that is was able to not only keep the chill off me but meant the entire room was toasty all winter. 

DeLonghi TRD40615E Dragon 4 Oil filled radiator review: price and availability

The DeLonghi Dragon 4 has been on the market for around three years, making it relatively new in heater terms. It has a list price of $149.95 though you can pick it up for slightly less online. Though other DeLonghi Dragon 4 models are available the UK and Australia, this exact model isn't. 

DeLonghi TRD40615E Dragon 4 oil filled radiator

(Image credit: Future)

DeLonghi TRD40615E Dragon 4 Oil filled radiator review: design and features

The DeLonghi Dragon 4 is larger than many of the basic six or seven fin oil-filled models, measuring around 14 inches long, 6.5 inches wide and standing around 25.5 inches tall. This is still compact enough to sit next to my office chair but a little too tall to fit under a desk – plus with the heat radiating from the top, that probably isn't advised anyway. 

Rather than the usual fin-like design, the sides of the Dragon 4 are flat strips. These are actually triangular tubes mounted vertically and create a chimney effect. The idea is that the central core heats these tubes and the heat rises quickly out of the top as well as out of the sides, to warm the room faster. The top also has five large openings to allow the warm air to rise. 

The controls are all on the front end of the radiator and comprise six main buttons for the thermostat, power level, timer, dimmer and on/off. A larger Eco button sits below these and an LCD screen sits above. The screen provides the thermostat temperature – that it's set to rather than the current temp – as well as icons for the power level (min, med, max), heating status, power, timer and lock functions. 

The timer, like those on many heaters, only allows you to set a time to turn it off rather than to turn it on, but it does provide a 24-hour range in 30 segments. The Eco function will automatically change the power level to provide more economical heating. There's also an anti-freeze function that activates when the thermostat is set to 41ºF and will only turn on when the room drops below this temperature. This is ideal for garages or basements. 

The radiator is mounted on four caster wheels that rotate to allow for easy movement in any direction. There are also grab handles on both ends of the unit to pick it up if needed. 

DeLonghi TRD40615E Dragon 4 oil filled radiator

(Image credit: Future)

DeLonghi TRD40615E Dragon 4 Oil filled radiator review: performance

There's no fan noise with an oil-filled radiator but that is an audible pop and crackle as the oil first heats. In the DeLonghi Dragon 4 these are only noticeable in the first couple of minutes of turning the device on. After that, the radiator is completely silent. If you set the thermostat to a lower temperature there is a quiet click when it reaches temperature and when it resumes heating but you'd only hear it if you were sat in silence. 

The Dragon 4 did what no fan heater seemed to be capable of, and that was to properly heat my entire office, even when it was approaching 0ºF outside. As the heat isn't directional, it takes a while to feel the benefit, but you can feel the heat coming out of the top of the radiator if you hold your hands over it. 

The actual coverage that is offered by the radiator isn't immediately clear as the website suggests use for rooms up to 145 sq ft, which is considerably less than the 250 sq ft provided by the smaller and cheaper DeLonghi Radia S Eco model. The larger panels and chimney design certainly suggest the Dragon 4 is the more powerful of the two and it certainly had no problem covering my 160 sq ft room. 

DeLonghi TRD40615E Dragon 4 oil filled radiator

(Image credit: Future)

DeLonghi TRD40615E Dragon 4 Oil filled radiator review: verdict

Feature-wise, the Dragon 4 is very similar to the DeLonghi Radia S Eco, with the exception being the chimney fin panel design. This design not only looks more stylish but it does heat the room faster. 

There's nothing that this model is lacking and the only more advanced model in the range (the Dragon 4 Pro) simply adds a more effective timer. If you really wanted to use this kind of heater with a timer, you could always add a smart plug, that way you can easily schedule it to turn on or off as often as you like. 

If you are looking for a reliable oil-filled radiator, the Dragon 4 is an excellent choice. However, for $20 less, the Radia S Eco is probably good enough for more users. 

DeLonghi TRD40615E Dragon 4 Oil filled radiator review: also consider

Unless you particularly need the fast heating functionality, the DeLonghi Radia S Eco models are a great option and come in $20 to $50 cheaper than the Dragon 4. It's also slightly smaller if space is an issue. 

If you're looking for a heater that you can use all year round, take a look at one of the Dyson Pure Hot + Cold models that allow the fan to be used both with and without the heating element to either heat or cool. New models, such as the Pure Hot + Cool Formaldehyde HP09 also include an air purifier. 

Mat Gallagher

As T3's Editor-in-Chief, Mat Gallagher has his finger on the pulse for the latest advances in technology. He has written about technology since 2003 and after stints in Beijing, Hong Kong and Chicago is now based in the UK. He’s a true lover of gadgets, but especially anything that involves cameras, Apple, electric cars, musical instruments or travel.