Oil Filled Radiator vs Convection Heater: Which Should You Source?

A buyer in Poland asked me last month why his oil-filled radiator returns were double his convection panel returns. Same wattage, same room size. The difference comes down to how each one moves heat, and if you're sourcing for a specific market, that difference decides your SKU mix.

How they actually heat a room

A convection heater pulls cold air in at the bottom, runs it past a finned element, and pushes warm air out the top. It heats the air. The air moves. The room warms in 10 to 15 minutes. Turn it off and the warmth is gone in 20.

An oil-filled radiator heats a sealed body of thermal oil, which then radiates and convects heat off its surface. It takes 20 to 30 minutes to hit full output. But after you switch it off, it keeps releasing heat for another 20 to 30 minutes. That lag is the whole story.

If your customer wants fast heat in a room they use for an hour, convection wins. If they want steady background warmth in a bedroom overnight, oil wins. This is why "silent electric heater" searches skew heavily toward oil-filled units. No fan, no click, no airflow noise. Just a hot metal surface doing its job.

Wattage, room size, and the numbers buyers get wrong

Standard rule: 100W per square meter in a well-insulated room, 150W if insulation is poor. A 2kW oil-filled radiator is rated for roughly 20 square meters. A 2kW convection panel is rated for the same, but it will feel warmer faster and colder faster.

Here's where buyers get burned. They order 2kW units for a 30 square meter open-plan space and wonder why reviews say "doesn't heat the room." It's not the product. It's the sizing. If you're selling into the UK or Germany, put a room-size guide on the box. It cuts returns more than any thermostat upgrade.

For a low wattage electric heater under 800W, oil-filled is almost always the better format. A 700W convection panel feels weak because the air it moves is barely warm. A 700W oil radiator feels warmer because the surface area is larger and the heat is radiant as well as convective.

Where each format actually sells

Convection panels dominate wall-mounted applications. If your buyer is sourcing a wall mounted electric heater for a bathroom, office, or rental apartment, convection is the default. Slim profile, cheap to ship, easy to install. IP24 bathroom versions need a pull cord or a sealed rocker switch, and the element has to be rated for damp conditions. Don't skip that.

Oil-filled radiators dominate portable and semi-permanent heating. They're heavier, so shipping cost per unit is higher. A 2kW oil unit weighs 10 to 12kg. A 2kW convection panel weighs 3 to 4kg. That freight difference matters at 200 pcs MOQ. If your buyer is comparing landed cost, oil-filled loses on freight and wins on perceived value. Consumers pay more for the weight and the silence.

Infrared is a different animal. Infrared heater vs convection is not a fair fight because they heat different things. Infrared heats objects and people, not air. Great for a garage or workshop where the door opens and closes. Useless for a bedroom where you want the air warm. Don't let a buyer talk you into stocking infrared as a general-purpose room heater.

Thermostats, WiFi, and what buyers actually ask for

A mechanical thermostat on an oil-filled radiator is a bimetal strip. It works, but it swings 2 to 3 degrees. A digital thermostat holds within 1 degree. For a best electric heater with thermostat positioning, digital is the safer spec if you're selling on Amazon and reviews mention temperature swings.

WiFi smart electric heater models add 8 to 15 USD to the BOM depending on the module and app. The app is the hard part. If you're a private label brand, you need a supplier who already has a stable app, not one who will build it for you. Ask for the app's active user count and the last firmware update date. If they can't answer, walk.

Certifications and lead times

For Europe: CE, RoHS, and ERP Lot 20 compliance on the controller. ERP is the one buyers forget. A non-compliant thermostat can get your shipment stopped at customs. For the UK: UKCA. For North America: ETL or UL, and you need the right plug type.

Standard MOQ is 200 pcs per model. Mixed containers are possible but expect a 15 to 45 day lead time depending on whether you're taking stock or custom tooling. Custom colors and logo printing add 5 to 10 days. Custom housing tooling adds 30 to 45 days on top.

One honest takeaway

Don't stock both formats just to cover the market. Pick one based on your customer's use case. If they heat rooms for short periods, convection. If they heat bedrooms overnight or want silence, oil-filled. Carrying both splits your inventory and your marketing. The buyers who win are the ones who own one position clearly.