I'm in Florida and have a 400 sq foot room that is nearly all
windows. It is the kids play room, but is only used seldom in the
evenings and is used on the weekends. Ideally, I'd like to only A/C
that room when it is being used.
I have sealed French doors that can close the room off to the return
duct. So I hoped that when the door was shut, there would be positive
pressure in the room that would act to shut off the 2 A/C ducts. But
it does not. Cold air still blows from them. I can only assume there
is a lot of leakage in the room around windows, etc. So my plan is to
spend a weekend sealing everything I can.
However, if the air still comes out a significant amount, I would like
to install motorized ducts assuming it does not cost a small fortune
(more than $200 per duct). I don't need variable control. Just on
and off. Either controlled by timer or by simple switch. I thought
about installing a linear actuator myself to control the flapper in
the existing register, but it would have to be on the outside and
would be visible in the room.