Oil filled radiator vs convector vs fan heater: which costs least to run in Ireland?
John Phelan
Same wattage, same cost. A 2kW oil filled radiator, a 2kW convector heater and a 2kW fan heater each cost about 76 cent an hour at full power in Ireland, because every electric heater turns its electricity into heat. What separates them is how fast they warm a room, how long the warmth lasts once they switch off, and which room each suits. This guide compares three Titan portable heaters we stock, with the running cost maths shown.
Quick answer: which costs least to run?
Per hour at full power, none of them. All three are 2kW heaters, so each costs about 76 cent an hour at Electric Ireland's standard rate. The cheapest one to run is the one that suits how you use the room.
For a room you sit in all evening, the oil filled radiator usually uses the least electricity, because its stored heat keeps the room warm while the thermostat holds the element off. For a room you need warm for twenty minutes, the fan heater wins, because it heats almost instantly and you switch it off again. The convector sits between the two.
The three heaters side by side
| Heater | Heat settings | Heat up speed | Heat retention | Best room use | Cost per hour at full power |
|---|---|---|---|---|---|
| Titan 2kW Oil Filled Radiator | 800W, 1200W, 2000W | Slowest, the oil warms first | Best, keeps radiating after switch off | Living rooms and bedrooms used all evening | 2 kW x 38.04c = 76c |
| Titan 2kW Convector Heater | 750W, 1250W, 2000W | Fast, warms the air within minutes | Low, cools quickly once off | Home offices and spare rooms used for an hour or two | 2 kW x 38.04c = 76c |
| Titan 2kW Letterbox Fan Heater | 1000W, 2000W | Fastest, warmth almost instantly | Lowest, the heat stops with the fan | Box rooms, sheds, caravans and quick top ups | 2 kW x 38.04c = 76c |
Room size guide from the product specifications: on full 2000W, the oil filled radiator and the convector each suit rooms up to about 20 square metres. Allow roughly 100 watts per square metre as a general rule.
How much does each heater cost to run per hour?
At 38.04 cent per kWh, the oil filled radiator costs 30 to 76 cent an hour, the convector 29 to 76 cent, and the fan heater 38 or 76 cent, depending on setting.
The unit rate used is the Electric Ireland 24 hour standard unit rate from 1 July 2026, which is 38.04 cent per kWh including VAT. The formula is wattage in kW x hours x unit rate. Check your own bill, as rates vary by supplier and tariff.
| Heater and setting | Power in kW | Maths | Cost per hour |
|---|---|---|---|
| Oil filled radiator, low | 0.8 | 0.8 x 38.04c = 30.43c | about 30 cent |
| Oil filled radiator, medium | 1.2 | 1.2 x 38.04c = 45.65c | about 46 cent |
| Oil filled radiator, full | 2.0 | 2.0 x 38.04c = 76.08c | about 76 cent |
| Convector, low | 0.75 | 0.75 x 38.04c = 28.53c | about 29 cent |
| Convector, medium | 1.25 | 1.25 x 38.04c = 47.55c | about 48 cent |
| Convector, full | 2.0 | 2.0 x 38.04c = 76.08c | about 76 cent |
| Fan heater, low | 1.0 | 1.0 x 38.04c = 38.04c | about 38 cent |
| Fan heater, full | 2.0 | 2.0 x 38.04c = 76.08c | about 76 cent |
These figures assume the element heats for the full hour. All three heaters have an adjustable thermostat that cycles the element off once the room reaches your set temperature, so the real cost of an hour is lower. If you are on a day and night meter, the same source lists a night rate of 20.03 cent per kWh, which brings a full power hour down to about 40 cent.
Which heater warms a room fastest?
The fan heater. It blows warm air straight into the room, so you feel the warmth almost instantly. The convector follows within minutes, and the oil filled radiator is slowest.
The oil filled radiator has to heat its sealed oil before that oil heats the room, so switch it on a little ahead of time, or choose the model with a built in 24 hour timer and let it start before you get home. The convector also comes as a timer model.
Which heater keeps a room warm longest?
The oil filled radiator. Its warm oil keeps radiating heat after the thermostat switches the element off, so the room stays comfortable while it draws no power.
A convector heats the air directly and cools quickly once it switches off. A fan heater stops producing heat as soon as its element and fan stop. That difference in heat retention is the reason the oil filled radiator suits long evenings and the other two suit short sessions. For the same question with a wall mounted panel heater, see our panel heaters vs oil filled radiators comparison.
Which is best for a bedroom, living room or home office?
Oil filled for bedrooms and living rooms, as it is near silent and holds heat. Convector for home offices and spare rooms. Fan heater for box rooms, sheds and quick top ups.
- Bedroom: the oil filled radiator has no fan, runs near silently and has a tip over safety switch. The convector is also near silent if you want faster heat.
- Living room: the oil filled radiator, for steady warmth across an evening, with castors to move it between rooms.
- Home office: the convector, which warms the air within minutes and can stand on its feet or be fixed to the wall.
- Box room, shed or caravan: the letterbox fan heater, slim enough to sit under a desk, with a cool blow setting for summer.
- Bathroom: none of these. Use a heater made for the room from our electric towel rails and bathroom heaters range, fitted by a registered electrician.
How to cut the running cost of any portable heater
Use the thermostat, run it on a timer, size it to the room and keep doors closed. Those four habits save more than choosing one heater type over another.
Set the thermostat to the temperature you actually want rather than leaving the heater on full. Pick the timer models of the oil filled radiator or the convector if the heater might otherwise run in an empty room. Match the wattage to the room, because an undersized heater runs flat out and never satisfies its thermostat. Our guide to the most energy efficient electric heaters covers the controls that make the biggest difference.
Frequently asked questions
Are oil filled radiators expensive to run?
No more than any other heater of the same wattage. The Titan 2kW oil filled radiator costs about 76 cent an hour at full power, and less on its 800W and 1200W settings.
Is an oil filled radiator cheaper to run than a fan heater?
Per hour at the same wattage they cost the same. Over a long evening the oil filled radiator often uses less, because its stored heat keeps working while the element is off.
Is a convector heater cheaper to run than an oil filled radiator?
Not per hour, as both reach 2000W. A convector can cost less for a short session because it warms the room quickly, while an oil filled radiator is better value over several hours.
What unit rate did you use for the running costs?
38.04 cent per kWh including VAT, the Electric Ireland 24 hour standard rate from 1 July 2026. Multiply the heater wattage in kW by the hours and by your own unit rate to check your figure.
Do I need an electrician for a portable heater?
No. The oil filled radiator and the fan heater plug into a standard socket, and the convector stands on its feet out of the box. Only wall mounting or bathroom heating needs more.
Where can I buy portable heaters in Ireland?
From Shamrock Electrical, online with free delivery to every county in the Republic of Ireland from the first euro, or over the counter at our store in Rathcoole, Co. Dublin. Call 01 401 9907 for help choosing.
Shop portable heaters, free delivery across Ireland
Browse all three in our portable electric heaters range: the Titan 2kW Oil Filled Radiator, the Titan 2kW Convector Heater and the Titan 2kW Letterbox Fan Heater. For fixed heating see wall mounted electric heaters or the full electric radiators and heaters range. Every order ships free to every county in the Republic of Ireland with no minimum spend. Website prices are retail; for trade pricing call 01 401 9907 or email sales@shamrockelectrical.ie.