Running cost
Quick answer
Oil radiators typically draw 1,500–2,500 W (about 39–65p an hour at 26p/kWh). A 600 W plug-in heater costs about 16p an hour.
Heat-up time
Oil radiators take 20–40 minutes to warm up. A ceramic plug-in heater reaches full heat in seconds and warms a room in 10–15 minutes.
Size and convenience
Oil radiators are heavy and take floor space. Plug-in heaters sit on the socket with no cable.
When an oil radiator makes sense
For long, steady background heat in a large room, an oil radiator can work well. For quick, cheap heat in one room, a plug-in heater wins.
Does an oil-filled radiator keep heating for free after switch-off?
It continues releasing stored heat, but that warmth is not free. Electricity previously heated the element, oil and metal body. After switch-off, this stored energy gradually passes into the room. The radiator does not produce extra energy simply because it stays warm to the touch.
That slower release can feel pleasant during steady use. It can also mean warmth arrives after you wanted it or continues after you leave. Whether that matters depends on your routine, the controls and how quickly the room cools down.
A ceramic fan heater generally delivers heat more promptly through moving air and has less useful stored warmth after switch-off. Neither response is inherently more efficient at converting electricity into room heat. The practical question is which pattern supplies warmth when and where you need it.
Can a 2 kW radiator use less electricity than its label suggests?
Yes. The rating usually describes maximum input, not a promise that the appliance draws that much continuously. A thermostat may switch heating off for part of the time, and some radiators offer lower power settings. Check the specific model rather than treating every oil radiator as permanently running at maximum.
For example, a 2 kW element operating for a total of 18 minutes during an hour uses 0.6 kWh. That is the same energy as a 600 W heater running continuously for the hour. This is an illustration, not an expected duty cycle.
The comparison explains why the bigger hourly price does not settle the buying decision. Both appliances must replace the room's lost heat. Controls, placement and overshoot may affect actual use, but neither element type gives a special exemption from that heat requirement.
Which heater is better for short visits to a room?
A quick-response fan heater may suit a room used for a brief reading session or a short spell at a desk. It starts moving warm air soon after switch-on. An oil radiator first warms its internal components, so its useful response may be less immediate.
However, a universal 20–40 minute oil-radiator warm-up claim is too broad. Models, starting temperatures and chosen settings differ. Likewise, Varmo's roughly eight-second ceramic-plate warm-up is not a measurement of how quickly every room reaches a comfortable temperature.
If you often use the room briefly, consider how much time is available for supervised pre-warming. If you occupy it for hours, the early warm-up difference may matter less than noise, controls and sufficient output. Do not buy on response time alone while overlooking the room's actual heat loss.
Is an oil radiator better for a large or draughty room?
It may be, if it provides the output the room needs. The reason is available heating power, not the oil itself. A small oil-filled radiator can also be underpowered, while a larger fan heater may deliver more heat than either of the models being considered.
Varmo is designed for one normal room, not a large open-plan space. A room with several open doorways, a high ceiling or substantial draughts may exceed what its 600 W can maintain. The heater cannot compensate for that by being set to a higher target temperature.
If the room stays cold, review draughts and insulation without blocking intended ventilation. For regular heating of a difficult space, consider a properly sized fixed system. Several compact heaters are not automatically a cheaper or more practical answer than one suitable appliance.
Which type is safer around furniture and walking routes?
The risks differ, and neither type is safe in every position. An oil-filled radiator occupies floor space, has a cable and can have hot surfaces. It needs a stable position where it will not obstruct movement or sit against curtains, upholstery or stored items.
A socket-mounted Varmo avoids a cable across the floor, but the socket must have adequate clearance. A socket behind a sofa or under hanging fabric may make it unsuitable. Its rotating plug helps with orientation only within the manufacturer's permitted arrangement.
Plug portable heaters directly into a sound wall socket. Never cover either type or dry clothes on it. Follow the instructions, keep children and vulnerable users in mind, and switch off before sleeping or leaving it unattended. Safety features do not cancel these precautions.
Should I replace an oil radiator that already works?
Not just because a smaller heater has a lower hourly headline cost. You have already paid for the radiator, and it may have a thermostat or lower setting that suits the room. First check how you currently use it and whether a simple change would avoid unnecessary heating.
Varmo costs £59 for one unit. To justify that purchase financially, the new arrangement must reduce total energy costs enough to recover the price. A change in element material alone does not establish any saving. Convenience, storage and room layout may still be valid reasons to change.
If the existing radiator is damaged, leaking or behaving unusually, stop using it and follow appropriate repair or disposal advice. Do not continue using a suspect appliance solely to avoid buying another. Compare safe, working alternatives and their suitability for your routine.
How can I compare the two fairly at home?
Choose the same enclosed room and a similar comfort target. Record the starting temperature, outdoor conditions and occupied hours. A test on a mild afternoon is not directly comparable with one on a freezing evening, even if both heaters run for the same duration.
Compare total energy used to maintain useful warmth, not just the heat felt beside the outlet. Include any pre-warming period and note whether the room remains comfortable. Whole-home meter readings also include other appliances, so they need careful interpretation rather than being treated as a precise heater test.
Do not use an unsuitable plug-in monitor, adaptor or extension to measure a heater. Ask for qualified advice if measurement equipment would alter the required connection. Even a careful home trial is an indication for that room and routine, not evidence of a universal saving for every household.
| Example rated output | One hour | Six hours | Heat supplied in six hours |
|---|---|---|---|
| 600 W | 15.8p | £0.95 | 3.6 kWh |
| 1,500 W | 39.5p | £2.37 | 9 kWh |
| 2,000 W | 52.6p | £3.16 | 12 kWh |
| 2,500 W | 65.8p | £3.95 | 15 kWh |
Pros and cons
Good points
- Varmo is compact and avoids a floor-standing appliance where a safe wall socket is available.
- Its quick element warm-up can be useful for short periods of supervised room heating.
Things to know
- An oil-filled radiator may be preferable when fanless operation matters.
- A 600 W plug-in heater has less available output than a larger radiator.
- Socket placement may be less flexible than the position of a floor-standing heater.
Who it is not for
We'd rather you buy the right heater than return the wrong one. Varmo is probably not for you if:
- You want Varmo to replace a higher-output radiator in a room that genuinely needs that heat.
- You need a fanless appliance.
- Your wall sockets cannot provide the required clear space.
How we worked this out
The table multiplies rated kW by operating hours and by 26.32p/kWh. It assumes continuous full output, not a prediction of thermostat-controlled consumption.
The electricity rate is Ofgem's average Direct Debit figure for 1 October–31 December 2026. Electricity has no VAT during October 2026–March 2027; actual tariffs and regional rates differ.
The daily standing charge, purchase costs and maintenance are excluded. Warm-up descriptions are not results from a side-by-side test, and no fixed percentage saving is assumed.
More questions answered
Sources
Facts on this page were checked against these independent sources. Energy prices use the Ofgem price cap for 1 October to 31 December 2026.
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