• Relatively short heating up times and good control possibilities • Short mounting times due to their small total weight • Minimum loss of heat – Double shell design allows to recover a great deal of the heat flow • No need of drying and warming up • Individual process-dependent control is possible because there is practically no stored heat • Wide range of control • Low operating cost • Ability to heat combustion air upto 100 ºC – 120 ºC to gain combustion efficiency