Сabin heater block BOK is stationary, with a continuous operating mode, designed to provide thermal conditions (microclimate) in the trolleybus driver's cab.

The cabin heater unit has two sections of heating elements (heaters): EH1...EH10 and EH11...EH20. This allows to organize two modes of thermal performance: full and half.

The unit is equipped with a three-stage fan blowing the heating elements. This makes it possible to ensure optimal supply of heated air to the driver's cab in the cold season, as well as to ensure the necessary cabin ventilation mode in the warm season (without turning on the heating elements).

The cabin heater block is equipped with an electric air damper that provides two modes of operation:

– intake of outside air into the unit for ventilation or heating,

– air intake from the cabin (recirculation) for accelerated heating.