In order for the circulation of the coolant to occur naturally, it is necessary to create some conditions to ensure the continuity of this process. Heating of the coolant should occur at a level lower than the heating radiators are located. The pipes on which the coolant circulates must have a fairly large diameter so that the coolant does not meet resistance when passing pipes. And, of course, when the coolant is received into the radiators of heat loss in the pipes, it should be minimal, so the PND pipes provide good thermal insulation.
