Creating pressure-relief loops in high-rise stacks of sanitary sewage installations

Product	InstalSystem 5
Type of article	TIP&TRICK
Source for translation	2026-06-04

Problem description

In stacks of Sanitary drainage installation where the difference in height between the highest and lowest connections exceeds 12 m, pressure builds up in the lower part, adversely affecting Fixtures connected near the base of the Stack.
Such Fixtures should be connected to an additional Stack, which is connected to the main Stack by a vent loop that equalizes pressure differences during operation of the Fixtures.

Solution

• The additional Stack is created automatically when a non-zero value is specified for the Number of storeys with additional stack field in the Data table window. The ventilation loop in the upper part is created and connected automatically. The additional Stack should be connected to the sewage installation manually, maintaining the required distance from the connection point to the base of the main Stack.
  

  

  1. Additional Stack.

  
  
• If no Fixtures are connected to the additional Stack, it should be connected to the sewage installation using the Ventilation conduit element.
  

  

  2. Additional Stack without connections.

  
  

The examples described, relating to stacks, in which the difference in height between the highest and lowest connections is more than 12 m, are presented in this file: Pressure-relief loops in high-rise stacks, isproj

More examples of applying bypass ventilation in sanitary sewage installation could be found here: Sewage installations - Bypass ventilation.

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