Could someone please explain why there are 2 types of space heaters– one that is convective and one that is infrared? Why does the first one not radiate and why does the second one not heat the air?
I know also that a convective heater is built with a spiral wire over a ceramic core that act like a resistor that gets heated.
How exactly is infrared heater built?
Best Answer
A human body feels heat while in contact with the air, so it is desirable to heat the air. This is what convectional heaters do - they have a developed surface and relatively low temperature to transmit the heat to the air. The radiation power is proportional to the following temperature difference: $Q \propto (T_{heater} ^4 - T_{air} ^4)$, so it can be small. The heater transfers its heat mainly to the air and the air transfers it to the walls.
The radiating heater has small surface, but much higher temperature so its radiating power is the main heat transfer (it works just like a lamp). The infrared waves get on the skin and heat it. Otherwise they get on the walls and heat thick walls. The radiating heater heats the air too, but due to too high temperature this hot air goes straight up and heats the ceiling, so it is poorly mixes with the room air.