heat exchanger with a safety system for the indirect heating of drinking water and in which the heating side and the drinking water side are separated by two walls; the space between tho walls is filled with a medium, soojusvaheti, millel on joogivee kaudseks soojendamiseks mõeldud turvasüsteem ja mille kütte- ja joogiveepool on eraldatud kahe seinaga, kusjuures seinte vaheline ruum on täidetud vedeldiga