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Setting the Airflow

This tutorial teaches you how to set the airflow for your diffusers.

Open drawing M-1.0.

Set Total Airflow in a Room​

If you are using Design Master HVAC to calculate loads for your project, you can set the total airflow based upon the room.

  1. Run the Set CFM Total in a Room command.
    Ribbon: DM HVAC→Diffusers→  Set CFM Total in a Room
    Pulldown Menu: DM HVAC→Set CFM Total→In a Room

  2. Select a point inside the lobby. The Set CFM Total in a Room dialog box will open.

  3. In Supply Air, set New CFM to 1200.

  4. In Return / Exhaust Air, set New Return CFM to 1200.

  5. Make sure 🔘 Prorate CFM in Diffusers is selected.

  6. Press the button to close the dialog box.

The airflow will be distributed among the supply diffusers in the room.

Because 🔘 Prorate CFM in Diffusers was selected, diffusers will keep any proportional differences: the 200 CFM diffusers are now set to 220 CFM; the 100 CFM diffusers used half as much airflow, and still use half as much at 110 CFM.

Because diffuser CD-1 has a range of 0-200 CFM, the diffusers with 220 CFM have automatically changed to CD-2.

Set Total Airflow in Multiple Diffusers​

If you are using an external program to calculate loads for your project, you can set the total airflow for groups of diffusers.

  1. Run the Set CFM Total in Multiple Diffusers command.
    Ribbon: DM HVAC→Diffusers→  Set CFM Total in Multiple Diffusers
    Pulldown Menu: DM HVAC→Set CFM Total→In Multiple Diffusers

  2. Select the supply diffusers inside the concession area. The Set CFM Total in Multiple Diffusers dialog box will open.

  3. Set New CFM to 400.

  4. Press the button to close the dialog box.

The airflow will be distributed among the selected diffusers.