Query Duct

To modify a duct that is shown on the current drawing, go to

DM HVAC->Duct Centerlines->Query Duct

Select the duct on the drawing to be queried. The information in the database regarding the selected duct will be displayed in the Duct Information dialog box.

Duct Centerlines--Query Duct.Duct Information dialog box

Changes can be made to the duct in the same way as when it was inserted. See the Common Duct Information section for more information.

The airflow information in the dialog box is specific to the Query Duct command.

Recalculate Size: Press this button to recalculate the size of the duct. The current settings in the dialog box will be used.

CFM: This is the volume of air in cubic feet per minute (CFM) that is traveling through the selected duct.

CFM Lock: Whether or not the CFM value is locked. If this box is checked, the CFM is locked at the specified value. If it is not checked, the CFM value is calculated based upon the airflow through the diffusers connected to the ductwork.

CFM Diversity Factor: A diversity factor applied to the CFM value in this duct. The diversified CFM value is displayed in the CFM field and used for the ductwork calculations. The full CFM value is passed to the next duct when the CFM values are calculated.

Pressure Drop in this Section: The pressure drop through this duct. This is the pressure drop in the straight section of duct between the fittings. It is not a total pressure drop for the system and it does not include the fitting pressure drop.

Pressure Drop in this Section Lock: Whether or not the pressure drop through this duct is locked. Check this box to specify a specific pressure drop that is different from the calculated value.

Pressure Drop in Previous Fitting: The pressure drop through the previous fitting. See the Previous and Next Ducts sections for more information on identifying the previous fitting.

Static Pressure at end of Previous Duct (or Fan): The static pressure at the end of the previous duct just before the fitting or at the fan connected to this duct if there is no previous duct.

Static Pressure at end of Previous Duct (or Fan) Lock: Whether or not the static pressure at the end of the previous duct is locked. Check this box to specify a specific static pressure rather than have it calculated.

Total Pressure at end of Previous Duct (or Fan): The total pressure at the end of the previous duct or at the fan connected to this duct if there is not previous duct.

Total / Static Pressure at Start of this Duct (From Start): The total and static pressure at the start of the duct, as calculated from the fan.

Total / Static Pressure at Start of this Duct (To End): The total and static pressure at the start of the duct, as calculated from the diffusers.

Total / Static Pressure at End of this Duct (From Start): The total and static pressure at the end of the duct, as calculated from the fan.

Total / Static Pressure at End of this Duct (To End): The total and static pressure at the end of the duct, as calculated from the diffusers.

Velocity Pressure in this Section: The velocity pressure in the duct.

Estimate Brake Horsepower (70% efficiency): Fan size required based upon the total pressure in the duct.

Velocity: The velocity of the air flowing through the duct.

Pressure Drop per 100': The pressure drop per 100 feet in the duct.

Recalculate Velocity: Press this button to recalculate the velocity and velocity pressure in the duct when you have manually changed the size. The duct size and airflow are not recalculated when this button is pressed.


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