I'm not clear on how to model a mixed air handling unit in Sketchbox. It seems there's only a pull-down menu for a dedicated outdoor air system, which traditionally means a 100%OA AHU. Is this menu meant to describe any type of system that introduces ventilation air?
Hi,
There should be a pulldown menu labeled "Air-Side System" and a second menu that says "Dedicated Outdoor Air System" on the design screen. If you select the "None" option from the Dedicated Outdoor Air System menu, then whatever system you select from the Air-Side System menu will be a mixed-air system. (For example, the "Packaged VAV with HW Reheat" system will include mixed-air air handling units.)
If you select the "Rooftop Unit" option, then the primary air-side system will use zero percent outdoor air and the program will add a 100% outside air RTU that uses air-cooled DX cooling and a gas-fired furnace for heating. If you select the "Same as Primary HVAC System" option then the DOAS will use the same cooling and heating plant as the main air-side system (for example, a water-source heat pump or chiller and boiler).
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