How do I identify the pipes of my heating system?

  • detect flow and return
  • detect hot and cold water
  • circulation line
  • gas line

In general, it is better to leave extensive work on the heating system to a specialist. Smaller repairs can also be carried out by a loaner after a little research. Depending on the project, you can usually find many instructions and good tips on the Internet. Sometimes one lacks certain basic knowledge that is assumed. For example, which pipe is actually which. This is exactly the knowledge we want to impart today.

Heizungsrohre erklärt

How can I recognize flow and return?

Ideally, everything was marked during installation and the search is over. However, since this is almost never the case, you have to resort to other features. Recognizing flow and return is easy, because the flow is always warmer than the return. If you can’t feel the temperature difference directly, you can switch the heating on and off completely. The first line to get warm is the supply line. In addition, you can see the return flow at the expansion vessel. The expansion vessel is a small, roundish tub, which is intended to prevent damage to the system due to volume changes in the water.

How to recognize hot and cold water?

The simplest method is the same as for recognizing flow and return. As the name suggests, the hot water line is warmer than the cold water line. But there is another way to distinguish the two lines. Namely, the safety group is always attached to the cold water inlet of a water tank. Consequently, the line with the safety group is also the cold water line. Alternatively, you can also run the hot water at a tap and at the latest then the hot water line should become warm.

How to recognize the circulation pipe?

The circulation pipe helps to provide hot water directly when it is needed. In order for a circulation pipe to work, you also need a circulation pump, which provides the necessary power to circulate the excess water. And this is exactly how you can recognize the circulation pipe. The pipe on which the circulation pump sits is the circulation pipe. It is also the thinnest pipe connected to the hot water tank.

How do I recognize the gas line?

Die Gasleitung führt gradewegs zum Gaszähler, somit ist es möglich die Leitung zu verfolgen. Ansonsten lässt sich die Gasleitung auch an den gelben Absperrhähnen erkennen. Diese sind typisch für eine Gasleitung.


Identifying which task to assign to each pipe is basically easy if you know what to look for. The flow and hot water pipes are warmer than their counterparts. The return can be recognized by the expansion tank. The cold water line, on the other hand, has the safety group installed. If you want to locate the circulation pipe you only have to look for the circulation pump. If you are not sure you can contact us. Ideally, you send us a picture so that we can give you an accurate answer, alternatively, a specialist from the local area can help you.

Autor: Jan Bittner