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# About Pipe Network Calculation Heating and Cooling

Explains the concept of pipe network calculation for heating and cooling.

## Detection of Network Geometry and Components

Before calculation, the pipe network is detected from the drawing in all detail. This is done automatically after clicking Calculate. Only components of the layers that have been selected for component detection in the Settings dialog are detected.

To analyze the geometry of the pipe network, the section parts are determined first. Section parts in the pipe network will be delimited by T-pieces or by components of dimension changes (e.g. transitions).

The program then searches for the starting component of the pipe network. This consists, for example, of a boiler, a chill generator or a partial network start.

On this basis, the flow paths of the pipe network are determined. Flow paths always lead from an initial component to a radiator, a chill consumer, a partial network end or an FH manifold. The number of flow paths in a regular heating or cooling pipe network is thus always equal to the number of drawn consumers.

During network detection, material is automatically assigned to the pipes in in the drawing according to the settings in the Pipes and Insulations dialog.

## Calculation steps

Prior to calculation you can determine a number of parameters in the Settings dialog, limit values for velocities and the pipe friction pressure gradient (R-value).

When starting the pipe network calculation, the smallest dimension is selected for all section parts that have not been fixed. The smallest dimension always is the first active dimension in the pipe tables. If you do not wish to go beyond a certain dimension, deactivate smaller dimensions in the pipe tables.

The program determines the the required mass flow rates in the pipe network based on the mass flow rates of the consumers which can be set for each consumer individually. If a consumer contains information about its power output only, the mass flow rate is calculated using the specified supply- and return water temperatures. If for a partial network end only the heat flow rate is specified, the mass flow rate is also recalculated.

This mass flow rate is the basis for the calculation of the flow resistances in the pipe network. As soon as the limits for the R-value or the speed is surpassed, the program applies the next larger dimension to the affected section part (unless the dimension is specifically fixed). The basis for that procedure are the pipe tables.

The last step for the calculation is the hydraulic balancing. This is done by comparing the pressure losses in the flow paths and the throttling of all flow paths to the same pressure loss level, as it occurs in the most unfavorable flow path behind a pump.

The most unfavorable pipe run of the pipe network is recognized by the program automatically by determining all pressure losses for all flow paths first. This most unfavorable pipe run is marked in color in the table for flow paths of the calculation dialog. When pressing U on your keyboard, the most unfavorable flow path is selected in the table.

The network is then hydraulically balanced using regulating valves. To achieve this, differential pressure closed-loop controllers, flow regulators, regulating valves and radiator lockshield valves for radiator are useds.