[mharwell01]

I have a bonus room over my garage that I enter from my upstairs master bedroom. We use it as a huge closet, however there is no duct/return to it to regulate the temp. in the summer and winter. My bedroom has a cathedral ceiling and, therefore, no way that I can see to run a supply and return from my upstairs unit to the closet. I think I can run the supply and return from the unit in my basement and up the inside of the garage to access the bonus room from below. Im just not sure what's acceptable as far as the length of the run since Id be coming from so far away. Also, does the return and supply vent need to be located a certain distance or oriented in a manner so theyre not near each other or not?
The bonus room is about 12' by 20'. I dont necessarily care that it be heated and cooled as well as the rest of the house, Id just like to be able to go out there in the winter without freezing and the summer without sweating. Any thoughts or advice would be appreciated. The bonus room is finished and insulated.

 

[beenthere]

By code. Ducts in a garage must be concealed/enclosed.

The size of the ducts will be dependant on how long the run is.

As far as how close a return and supply can be to each other.
If using floor registers. They can be fairly close. But it work better. If you can keep them far apart. Since you probably won't be getting good throw.