Automatically Close Ducts

I am going to have all my equipment in a relatively small room (under the stairs). There will be at least one computer, A/V equipment including amplifiers, PoE switch, etc. I want to keep this room as cool as possible so an air duct for heat/AC will be routed in there (if possible). When the heater is on I obviously want to close it but when the AC is on I want the duct open. I am thinking of this one

I understand that closing the vent is actually bad for the efficiency of the system.

I might be ok if I use this for just one room but are there any other options? Also are there any z-wave fans which I plan to install in addition.

It’s only a problem if you shut supplies down to the point that the system isn’t operating at the correct pressure. You could also look at installing high/low registers in the wall. One near the floor and one near the top off the closet should keep it cool enough in there.