The given blank can be filled with convection heating systems.
A heater that works by air convection currents circulating through the body of the appliance, and across its heating element is known as a convection heater. This heats up the air, making it elevate in volume and so make it to rise and buoyant.
A convection heater may exhibit an electrical heater element, a steam coil, or a hot water coil. Due to natural ventilation, they are quieter in function in comparison to the fan heaters.