Riser / Stack
Overview
Design and size riser/stack systems to effectively distribute fluids and air vertically in your building model.
On each level, there could be results for the following directions:
To Above: These risers extend upward from a given floor to supply or exhaust fluid or air to levels above.
From the perspective of the current floor, a "to above" riser moves flow to the higher levels.
To Below: These risers extend downward from a given floor to supply or exhaust fluid or air to levels below.
From the perspective of the current floor, a "to below" riser moves flow through the floor to the levels below.
Flow Rate
Calculate the Peak Flow Rate, the maximum expected flow from connected fixtures, nodes, emitters, diffusers, or grilles.
Domestic Water
Specify parameters for domestic water flow rate calculations. Diversification adjusts flow requirements to reflect how much water the system needs to handle at its busiest. Continuous flow fixtures, like medical equipment, bypass diversification.
In the Methods
section, define the Peak Flow Rate Calculation Method
. Set Diversification
, Loading/Fixture Units
for each fixture/node, and Spare Capacity
(for future demand) in System Settings
.
A range of system settings determines Peak Flow Rate:
Peak Flow Rate Calculation Method: This setting specifies the calculation standard or method used to derive the peak flow rate.
This setting is defined in Methods.
Diversification adjusts flow requirements to reflect realistic peak demand rather than the maximum possible flow for every fixture. For example, in a residential system, not all fixtures will be used simultaneously; diversification accounts for this by applying a factor that reduces total calculated demand.
Loading/Fixture Units of Fixtures and Nodes: Each connected fixture or node has an assigned loading or fixture unit value, representing its contribution to peak flow based on expected usage.
This unit is assigned to each fixture or node in the design phase.
Higher loading units increase the peak flow rate, as these units are summed across all connected fixtures to determine total demand.
Continuous Flow Fixtures/Nodes: Fixtures or nodes that operate with a continuous flow (such as certain medical equipment) that bypass diversification. Instead, their flow rates are added directly to the peak flow rate calculation, representing a constant demand that does not vary.
Identified as continuous flow within node or fixture properties.
Continuous flow fixtures add directly to the peak flow rate without diversification, ensuring that the calculation fully accounts for constant demands..
Spare Capacity: An optional setting that adds a percentage increase to the peak flow rate for future demand or unexpected increases. Adding spare capacity ensures the system can handle higher-than-anticipated flows without the risk of undersizing.
Configurable in System Settings as a percentage added to the final peak flow rate.
Spare capacity increases the peak flow rate by a specified percentage, providing a buffer for demand fluctuations or future system expansions.
Peak Flow Rate is crucial for determining appropriate pipe sizing, system pressure requirements, and equipment capacity. By calculating the maximum expected demand, this metric helps ensure that the system can meet peak water requirements without performance issues.
If you want to troubleshoot this part of the system, it is recommended to:
Review the Water section of Methods
Review the relevant Systems
Export a Design Report and review all of the Fixture/Node values
Ventilation
Specify parameters for ventilation flow rate calculations. Each room typically has a different minimum ventilation flow rate requirement.
In the Methods
section, define the Vent Air Changes Rate Standard
. Set the Diffuser/Grille Flow Rate
for each diffuser/grille. Configure Spare Capacity
in System Settings
.
Peak Flow Rate is determined by a range of system settings:
[Optional] Vent Air Changes Rate Standard: This setting specifies the calculation standard or method used to derive the peak flow rate.
This setting is defined in Methods.
Each room typically has a different minimum ventilation flow rate requirement
Diffuser/Grille Flow Rate: This defines the flow rate assigned to each specific Dffuser/Grille.
Spare Capacity: An optional setting that adds a percentage increase to the peak flow rate for future demand or unexpected increases. Adding spare capacity ensures the system can handle higher-than-anticipated flows without the risk of undersizing.
Configurable in System Settings as a percentage added to the final peak flow rate.
Spare capacity increases the peak flow rate by a specified percentage, providing a buffer for demand fluctuations or future system expansions.
Peak Flow Rate is crucial for determining appropriate pipe sizing, system pressure requirements, and equipment capacity. By calculating the maximum expected demand, this metric helps ensure that the system can meet peak water requirements without performance issues.
If you want to troubleshoot this part of the system, it is recommended to:
Review the Mechanical section of Methods
Review the relevant Systems
Export a Design Report and review all of the Diffuser/Grille values
Size Pipes and Ducts
Size pipes and ducts based on flow rate, velocity, and pressure drop limits.
Pipes
Determine appropriate pipe diameters. In the Methods
and Systems
sections, set Maximum Velocity/Pressure Drop Limits
. Control available pipe sizes in System Settings
. Override these settings in Properties
if needed. You can also override pipe diameter directly in properties.
The Pipe Diameter is influenced by the following properties:
Flow Rate: The pipe diameter is sized based on the calculated flow requirements.
Maximum Velocity and/or Pressure Drop Limits: The maximum allowable velocity and/or pressure drop along the pipes in the system will not be exceeded based on the calculated flow rate
Set in the Methods and the Systems
Enabled Pipe Sizes: System settings control which sizes are available, restricting or enabling diameters based on project requirements.
Confirm that the appropriate pipe sizes are enabled/available in System Settings.
Overridden: The pipe diameter or the pipes maximum velocity/pressure drop setting can be overridden in itβs properties
If any segment of pipe looks high, it is likely due to this
If you want to troubleshoot the pipe diameter, it is recommended to follow these steps:
Review the flow rate
Refer to the flow rate section if you want to modify the flow rate
Review the Pressure Drop and Velocity Limits
You may want to modify these to increase or decrease the pipe size
Increase limits (higher velocity and pressure drop) to decrease pipe size
Decrease limits (lower velocity and pressure drop) to increase pipe size
You can set different sizing methods based on riser, mains or branches
Ensure you have drawn with the correct pipe type, and are updating the System associated
Verify Enabled Pipe Sizes
Confirm that the appropriate pipe sizes are enabled in System Settings.
Note it is the internal diameter that is used in the sizing calculation, not the nominal diameter
Analyze the Design Report
Export the Design Report Spreadsheet and review pipe-related parameters such as flow rates, veliocitties, nd pressure drops .
Use Heat Maps
Visualize areas of high pressure drop or velocity within the system to identify problematic segments.
Ducts
Determine appropriate duct sizes. Configure Maximum Velocity/Pressure Drop Limits
in Methods
and Systems
. Override duct sizes or velocity/pressure drop settings in Properties
.
The influencing properties of duct sizing are:
Flow Rate
The duct size is determined based on the calculated airflow requirements.
Maximum Velocity and/or Pressure Drop Limits
The maximum allowable velocity and/or pressure drop along the ducts in the system will not be exceeded based on the calculated flow rate.
These settings are configured in the Methods and Systems tabs.
Overrides
Duct size or maximum velocity/pressure drop settings can be overridden in the Properties tab.
If a duct size looks unusual, it may be due to an override in its settings.
To troubleshoot issues with duct sizing, follow these steps:
Review the Flow Rate
Check the flow rate section to ensure the values align with system requirements.
Adjust the flow rate if needed to influence the duct size.
Review Pressure Drop and Velocity Limits
Modify these limits to increase or decrease duct size:
Increase limits (higher velocity and pressure drop) to decrease duct size.
Decrease limits (lower velocity and pressure drop) to increase duct size.
Configure separate sizing methods for System Settings' mains, branches, or risers.
Ensure the duct is assigned to the correct system and matches the intended type.
Analyze the Design Report
Export the Design Report Spreadsheet to review duct-related parameters such as flow rates, velocities, and pressure drops.
Look for discrepancies or unusual values in the duct sizing.
Use Heat Maps
Visualize areas of high-pressure drop or velocity to identify problematic segments.
Check for Overrides
Inspect the Properties tab for any overridden sizes or limits.
Correct overrides if they conflict with the design parameters.
Loading and Fixture Units
Assign loading/fixture units to represent the expected demand of individual fixtures/nodes in a water supply system. These units contribute to the peak flow rate calculation. View the sum of units at a specific part of the system using the result filter.
Assign each fixture a unit value based on the chosen Peak Flow Rate Calculation Method
. Diversification factors convert the sum of loading/fixture units to reflect peak usage.
This result filter tells you the sum at this part of the system.
The following are influencing properties:
Assigned Loading/Fixture Units
Each fixture or node is assigned a fixture unit value based on the selected Peak Flow Rate Calculation Method, based on its expected water demand.
Fixtures with higher loading units contribute more significantly to the system's total demand.
Diversification Factors
Diversification converts the sum of loading/fixture units to reflect realistic peak usage.
In systems like residential water supply, not all fixtures operate simultaneously. Diversification applies a factor to reduce total demand and prevent oversizing.
As the total loading/fixture units increase, the peak flow rate grows, but the rate of increase diminishes due to the decreasing likelihood of all fixtures operating at once.
To resolve issues related to loading or fixture unit calculations, follow these steps:
Review Assigned Loading/Fixture Units
Check each fixture or node to confirm their loading/fixture units match your expectations.
Override the values in the Properties tab if needed.
Check Spare Capacity Settings
Verify the spare capacity percentage set in System Settings.
Adjust this value to provide an appropriate buffer for future demand.
Export the Design Report
Use the Design Report to review all fixture and node values.
Look for discrepancies, such as unexpectedly high or low loading/fixture units.