Water boilers Pellet Comfort are delivered as integrated heating devices that consist of a boiler with a capacity of 7 to 25 kW along with a burner, pellet tray and feeder. The devices are designed for heating in buildings where there is a central heating water installation (C.O.) and/or a usable water installation (CWU). 7-16 kW boilers are adapted to work in an open system, which means, among others, that the hydraulic system must have an open expansion vessel with an overflow pipe and be carried out in accordance with the applicable standards for open systems or adapted to work in the system with closed buffer.