DDG unit without other central heating system
DDG unit in combination with a gas or gasoline system
DDG unit in combination with a combined gas system (heating + hot water)
DDG unit in combination with sun heating systems
DDG unit in combination with classic gas or gasoline system and solar heating system
DDG unit in combination with a pressure accumulation vessel + solar heating system
DDG unit in combination with a floor or wall heating system and radiators
Heat exchanger for a separated circuit