For Stadler Altenrhein, we developed a very compact recirculation heating unit for mounting in the door columns of regional railcars for the Swiss operators RBS and LEB.
The heaters are activated upon the opening of exterior doors in the wintertime to aid the existing heating system when passengers entering the railcar would draw in cold air.
When doors open, the air recirculation heater will turn on. When doors close the system will continue to heat until an adjustable time period of 0-120 sec. has passed and turn of.