Heating connection in parallel and in series

Lower distribution with central ventilation via air ducts

The Two-pipe system is the most popular system for distributing the heat to the connected heating surfaces. Each heating surface is connected to the separate flow and return lines and receive the same flow temperature. The heating surfaces are made by setting the amount of water according to the heating surface design using a presettable valve. This process will hydraulic balancing called.

One distinguishes lower and upper distribution of the heating water volume flow.

In the lower distribution, which is common in today's pump heating systems, the flow and return lines are laid on the basement ceiling. The radiators are supplied with heating water from here through flow risers, which is returned to the boiler through the return lines, at the highest points central or local ventilation provided, but never one automatic swimming vent should have.
Bigger ones and widely ramified plants will / were with a central vent above Air ducts (DN 10). When venting, it is not necessary to ventilate the vent valves in the individual apartments. The Radiator flow connections to have pitch away from the radiator and the connections on the air line calculated exactly so that the pump does not push the water through the air line.
The lower distribution can cheaper compared to an upper distribution. The warming of the cellar can be disadvantageous, despite good ones Thermal insulation, be.