Free Trial Download and try today

Missing Roof Load

Posted on January 18th, 2010. Last updated on June 15th, 2023.

If you run an HVAC building load calculation and your roof load is 0, check to see if you have a plenum return defined. If you do, the roof load is included in the “Plenum” category in the system load. The roof load is not included in the room load at all. Whether you have a plenum return is specified by the zone that the room is in.

To check this, use the Edit Rooms command.

Select the room with 0 roof load. Beside the Zone field, press the Edit button to open the Zones dialog box. The Plenum setting is in the bottom-left of the dialog box. If it is disabled, use the Next, Previous, and Find buttons to look at other zones above the initial zone until you find the zone where Plenum Return is enabled.

Related Articles

Filter by
Post Page
HVAC Installation, Licensing, and Software Management AutoCAD Configuration HVAC Drafting Diffusers Ductwork Electrical Electrical Drafting HVAC Rooms HVAC General Load Calculations
Sort by

How to Reload Missing HVAC Ribbons and Pulldown Menus

Here are commands you can enter at the command line to reload ribbon and pulldown menu tabs for Design Master HVAC.


Duct-Mounted Diffusers

Design Master HVAC does not have a command specifically for inserting or connecting duct-mounted diffusers and grilles. However, you can approximate them by inserting the diffuser close to the duct to which it is mounted.


“Locked Layer” Error Message

Design Master typically unlocks any locked layers it needs to use to function. If it can’t, it will display an error message telling you to unlock the layers.


DM Entities Insert Skewed or in the Wrong Location

If your Design Master entities come in skewed or in a different location than the one you specified, try resetting your drawing view to “Top” and reinserting.


Manual J Calculations

Design Master does not specifically include Manual J as a calculation basis, but will provide results that are at least as precise.


Exporting Load Calculations (and Other HTML Outputs) to Excel

Some HVAC and Electrical reports can be exported as HTML files. Here are three easy ways to open those files in Excel.