Applying Special Inlet Fitting (Ventilation fitting) in high stacks of the sewage installation

Product	InstalSystem 5
Type of article	TIP&TRICK
Source for translation	2026-03-26

Problem description

The program provides the opportunity of applying Special Inlet Fitting in the sewage installation. Below is an example using a VBF (Ventilation Branch Fitting System), but the general using rules in InstalSystem 5.5 Sewage module for all producers are common.

Solution

• Declare the catalogue containing Special Inlet Fitting in the General data window / Types and default data as default for the Stack. For more information, see: Using catalogues and catalogues data in the project;
• Insert Special Inlet Fitting using right mouse button context menu for the Stack.
  Note: The triangle pointing "front face" of the stack implies the initial orientation of the fitting;
• Connect the appliances to the Special Inlet Fitting using Gravity sewerage Pipe-run.
  Note: Generally, it is recommended for the Toilet bowl (large waste flows) to be connected to the upper inlets; for the Washbasin, Shower tray, etc. (smaller waste flows) - to the lower ones. However, producers may impose their own limitations, please check the product documentation carefully.

The further path follows the standard procedure for Designing gravity sanitary sewage installations:

• Use Check connections;
• Run Sanitary drainage systems Calculations;
• Make necessary corrections;
• If the building has multiple storeys, once a typical storey has been satisfactorily completed, copy the installation to the other storeys;
• Run Sanitary drainage systems Calculations of the complete installation;
• Verify the Results;
• Generate Schematic views.