Are heaters just giant resistors?
Yes. elements such as an electric furnace, a local radiator and baseboard heaters are in fact a very hot giant resistance. an electric water heater is just a big resistance in a stainless steel tube in the water tank.
There are other types of radiators. a heat pump runs on electricity but works as an inverted air conditioner where the warm side is inside and the cold side is outside. you can even get heat pump water heaters. Of course, this type of heating is not just a big resistance.
Here’s the thing about electric heaters. no matter the cost or the cost of an electric heater. if you put in 1500 watts of electricity, you will only get 1500 watts of heat. it does not matter whether it is a ceramic heater, a quartz heater, an oil appliance or a radiant heater. they will all emit the same amount of heat for the same amount of electricity.
Now, a fan will help distribute the heat. a radiator is able to heat objects directly in front of it. an oil radiator gives off a pleasant and constant heat. but they will all come out the same heat.
Both a resistor and a heating element of an electric heater are built on the premise that some materials are better able to pass electricity than others. something like copper lets it flow easily and something like plastic does not let it run at all. resistances and, by extension, are constructed to provide something in between these two extremes.
The resulting resistance is almost like a kind of friction acting against electricity and naturally creates heat. Although this heat can cause problems with the electronics, that’s exactly what we want with the heating elements. The heating elements are designed with materials such as chrome or some ceramics to absorb the maximum amount of electricity and convert it into heat thanks to the defined resistance of these materials.