A twin-wall system, without insulation, usually used as a connection (along with the MKKS single-wall system with seal ) or as a standalone chimney, for condensing and turbo stoves. The inner pipe of the system is used for fume exhaustion from the boiler, while the channel between the outer and inner tube feeds air to the boiler. The system has grooves for the seals.
It is available in the Premium version – for gas and oil. The system can operate in wet conditions, at a temperature of up to 120°C