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I took some simple steps to test how long an oil-filled electric heater stays hot.
As I have several in my house, I put them in different rooms and let them reach maximum heat before I turned them off.
Then I spent up to an hour monitoring how hot the heater stayed at the top and the bottom of the appliance. The different parts actually cooled at different rates.
Let’s start with a summary of the results, before getting into the details and a money-saving tip.
How Long Does An Oil-Filled Electric Heater Stay Hot?
On average, it takes thirty minutes for an oil-filled electric heater (1500W) to cool to the point that it is no longer warming the surroundings.
It takes forty minutes for the entire metal casing to be cold to touch.
You may be wondering if I tested the appliances in a hot or cold climate and whether that makes a difference. The test was conducted in a mild climate when the outside temperature was 52 °F or 11 Celsius.
The house is well-insulated, and the rooms are the typical size of a modern suburban housing estate.
How The Heat Reduces Over Time
A typical oil-filled electric heater is about two feet high with long fins. Here is one of mine that keeps people nice and warm on the couch beside it!
They are dust magnets, so I cleaned this one up a bit for the shot!
But I wanted to point out that the top of the fins cooled at a significantly slower rate than the casing at the bottom. Let’s get into the details.
| Time After Turning Unit Off | Top Of Appliance | Bottom Of Appliance |
| 10 minutes | too hot to touch | too hot to touch |
| 15 minutes | too hot to touch | warm to touch |
| 20 minutes | uncomfortable to touch | slightly warm to touch |
| 30 minutes | slightly warm | room temperature |
| 40 minutes | metal is cold to touch | metal is cold to touch |
How I tested the heat
I could have used a thermometer, but I think that the “feel from touch” description is easier for people to understand.
I was literally placing the palm of my hand against the metal casing at the top and bottom of the unit.
This also gives you an idea of when the heat from the appliance doesn’t represent a problem for a child or pet. After twenty minutes, the top of the appliance would evoke an “ouch” if a small hand touched it. At thirty minutes, it’s just a little warm.
These appliances present more of a problem for a small person pulling them over as opposed to the heat from a cooling unit.
How does this apply to heating a room?
For people sitting on a sofa near a heater, how long do they get the benefit of heat after you’ve turned the appliance off?
Typically, the warmth keeps radiating from the top of the unit for about fifteen minutes.
Half an hour after turning the unit off, there will be no benefit of heat in the near surroundings. The top is still slightly warm but you’re not going to feel any heat unless you are right beside the unit.
By forty minutes, the metal casing is colder to touch than the air in the room. The top of the appliance has also cooled completely at this time.
How To Save Money With These Findings
What all this means is that you can turn off the heater when you’ll be leaving the room in about fifteen minutes.
You will save a bit of electricity and make the appliance a little more cost-effective.
