How do I make the hot deck of the dual duct system remain constant in a system?

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I am trying to model a University Building that has dual duct systems in it that run at constant and variable air volume. I have two questions that go with this:

1. Is there a way to make the dual duct system supply constant air? As far as I can see there is only the Dual Duct VAV that pairs with dual ducts.

2. Is there a way to ensure that the hot deck runs year round? I am designing for climate zone 5A, so naturally the heating numbers should dip in the summer months; however, this building supplies hot air year-round (thus why I am retrofitting it). I need the hot deck to continue to run even at a constant rate all year.