Shrinking tunnel with alternative heating system. Instead of heating by electric power the shrinking tunnel is indirectly heated with natural gas. Using primary energy you save massively energy costs. This technique is ideal for large shrinking tunnel (e.g. 1700 mm wide, 800 mm high). It is a safe and clean technique, because by indirect gas heating no exhaust fumes will be in the tunnel cap. The exhaust gases leave the machine by a separate chimney. The machine's specifications (i.e. passage in widths, heights and conveyor speeds) can obviously adapted tailor made to your demands