The difference, without the jargon
An electric radiator turns electricity into heat. One kilowatt in, one kilowatt of heat out. It is simple and it cannot be bettered: that is the physical maximum for anything heating by resistance.
A heat pump does not make heat, it moves it. It takes what is already in the outside air, even cold air, and brings it in. For the same kilowatt consumed it delivers several times more heat. In a coastal climate, where winter lows are rarely extreme, that performance holds up well.
What that means on the bill
Broadly, heating the same room with a heat pump costs a fraction of what it costs with an electric radiator. The gap is not a few cents: it is a multiple.
So in a property that already has air conditioning with a heating function, using that unit in January instead of dragging the radiator out of the store cupboard is the most profitable decision of the winter, and it costs nothing.
Where a radiator still makes sense
To warm a bathroom for ten minutes in the morning, an electric radiator is more practical: it is instant, needs no installation, and its efficiency hardly matters over ten minutes.
The same goes for a room used twice a year, or where there is no possibility of fitting an outdoor unit. The mistake is not owning a radiator, it is heating the whole house with one all winter.
What ruins a heat pump's efficiency
A dirty or poorly maintained unit loses a large part of what made it worth having. A loaded filter, an outdoor coil corroded by salt, a low gas charge: each one takes efficiency away, and together they turn a heat pump into an expensive radiator.
Hence the annual service. It is not only to make the unit last: it is to keep it worth running.
How to use it well in winter
A steady moderate temperature performs better than switching on and off. A unit starting from fifteen degrees to reach twenty-three uses more than one holding twenty all day, particularly in properties with walls that are slow to respond.
And point the airflow downwards in heating mode: warm air rises on its own, and plenty of units spend the winter heating the ceiling because nobody has touched the louvres since August.
