An oil-filled radiator for heating one room for hours: it warms slowly, keeps giving out heat after it switches off and, in Which? tests, cost a little over half as much per hour as a fan heater. A fan heater wins for quick bursts in a room you use briefly.
By the What to Buy For team · updated 27 September 2026
Oil-filled radiator
Fan heater
How it heats
Warms a reservoir of oil that gives out heat gradually
Blows air over a hot element
Warm-up
Slower than fan and convector heaters
Much quicker than other types
After switching off
About half an hour more heat in Which? tests
Heat stops with the fan
Noise
No fan; the thermostat clicks as it switches
The fan can be noisy
Settings on the pick
600W, 900W or 1.5kW
1kW or 2kW
Electricity on full
1.5kWh an hour
2kWh an hour
Weight on the pick
6.7kg, on castors
1.13kg, with a carry handle
Speed against staying power
Which? explains that an oil-filled radiator heats a reservoir of oil, which warms the room more slowly but for longer. In its tests the radiators kept heating for about half an hour after being switched off, and cost a little over half as much per hour to run as fan heaters, on average.
A fan heater blows heat straight into the room and gets going much faster than other types, which suits a cold spare room or study used for an hour. Which? warns that the fans can be noisy.
Working out the electricity
The Centre for Sustainable Energy's method is to multiply the power rating by the time the heater is on. The 1.5kW radiator on full uses 1.5kWh in an hour; the 2kW fan heater on full uses 2kWh.
Both picks have a thermostat, which holds the room at the temperature you set instead of heating flat out, so real use is below those full-power figures. Multiply the kWh by the unit rate on your bill to get the cost.
Safety for both
London Fire Brigade says to keep heaters well away from bedding, curtains and furniture, never to dry clothes on them, and to sit at least a metre away. Turn a heater off and let it cool before moving it, and check it is not on a recall list.
Electrical Safety First advises against running a heater from an extension lead, leaving it on while you are out or asleep, or using it overnight. It also notes that an oil-filled radiator's fins stay hot after use, so keep children away until they cool.
A 1.5kW oil-filled radiator for a small living room or study
For steady heat in a room up to 15m², the listing gives three heat settings up to 1.5kW, an adjustable thermostat and a safety cut-off. On full it uses 1.5kWh an hour, less once the thermostat takes over. The thermostat clicks as it cycles, so in a bedroom warm the room before bed and switch off, as Electrical Safety First advises anyway.
What buyers say
Buyers like
Warms a small or medium bedroom or home office well(5 of 10 reviews)
The thermostat switches it off once the room is warm, then holds it(4 of 10 reviews)
The heat lingers after it cuts out, unlike a fan heater(3 of 10 reviews)
Watch out for
Clicks when the thermostat cuts in, which can wake light sleepers(2 of 10 reviews)
Slow to take a cold room up to temperature on its own(2 of 10 reviews)
Our summary of the 10 reviews Amazon showed on 27 Sept 2026, counted by us.
More about this pick
Size
about 63 x 33 x 24 cm
Weight
7.7 kg
In the box
1 x RHOFR5001B, 1 x User Manual
Warranty
2 year manufacturer.
From the Amazon listing, recorded 27 Sept 2026. Sizes are the listing's own.
A 2kW fan heater for quick warmth in a room used briefly
For a room you use for an hour or two, Warmlite lists 1kW and 2kW settings, an adjustable thermostat and overheat protection. It weighs 1.13kg and stands upright or flat. The maker does not list a tip-over switch, so put it where it cannot be knocked over.
What buyers say
Buyers like
Warms a small room within minutes(6 of 13 reviews)
Small and light enough to move from room to room(4 of 13 reviews)
Simple controls, with two heat levels plus a temperature dial(4 of 13 reviews)
Watch out for
A few units were faulty from the start or failed early(4 of 13 reviews)
Our summary of the 13 reviews Amazon showed on 27 Sept 2026, counted by us.
More about this pick
Size
about 9.8 x 9.6 x 4.9 cm
Weight
1.1 kg
From the Amazon listing, recorded 27 Sept 2026. Sizes are the listing's own.
Price: we have checked it on 3 days; Amazon showed no discount of 10% or more on any of them.
