Dear All,

A couple of labs in an educational building I'm modeling have 10 VAV
terminal units connected to a 100% OA make-up air unit on the roof. The
make-up air unit is DX cooling and Gas heating, providing preconditioned
air to the VAV terminal units equipped with electrical heaters. The labs
contain fumehood/snorkel exhausts. I'm still in the wizard mode trying to
configure the system accurately to start with. I have a couple of questions:

1. As one unit serving several VAV terminal units, the make-up air unit is
neither a packaged or split single zone DX with furnace, nor a Packaged
multizone with furnace. One workaround I can think of is to model both the
labs with the 10 terminal units combined as one zone, but not sure if this
is the best approach.
2. Its a 100% OA system with no return but I can't seem to select a "no
return" option, the only available options for return air path are
direct/ducted/plenum. Can this only be dealt with in the detailed
interface, and if so, how?
Thanks for your help,
Ramana Koti.