Here is a photograph of my electric convection heater. Notice that it is painted white because it doesn't give off heat as infra-red. As its name implies, it gives off heat by convection.
Here is a photograph of the bottom of it looking up. The black bits are an electrical heating element which was running at 1200W when the photograph was taken. The element is at the bottom because it heats the air. The air expands and becomes less dense than the colder air around it so it floats up through the grill at the top of the heater. You mustn't cover those holes at the top because the hot air would be trapped inside and the unit would overheat and perhaps start a fire.
