How to draw A/C to second level in garage

[Stew308]

I have a fully insulated garage I'm just now finishing - open cell spray foam. Just installed a Mitsubishi 24k mini split. Here's my issue: I added a second story in the garage and the upstairs is obviously pretty stinking hot when the first floor is 75 degrees. Presently the only air exchange is thru the stairwell. What's the best way to "push" conditioned air upstairs? Fan in the stairwell or should I put a bathroom vent fan in the floor to draw AC upstairs and let the return fall down the stairwell? Both floors are about 500 square feet with 9' ceilings.

Stewart

 

[The Cobbler]

first question, is the AC unit sized appropriately to cool the extra space?
you will need a fair bit of CFM to push the cold air upstairs. I would look at a furnace fan or something ducted from the floor to the ceiling of upstairs

 

[Stew308]

thanks for the reply. I assume the unit was appropriately sized as the original plan was to condition the entire space then we decided to add the second level. A reputable HVAC company did the calc and install.

 

[tncatadjuster]

AC Infinity 6” super quiet variable speed. Amazon

 

[Stew308]

AC Infinity 6” super quiet variable speed. Amazon

are you referring to their inline duct fans? do you think this would be an option? https://www.amazon.com/dp/B0BFK144X5/?tag=atomicindus08-20

 

[tncatadjuster]

I have two of the 6” to move minisplit ac around my shop 3,400sf, 3 years continous use, very happy with product. If other products are as good then highly recommended. If you use the one i have you can scavenge air off floor with flex duct and vent it upstairs. easy enough to physically reverse it to bring heat down.

 

[Jackfre]

These work well. I have sold a few thousand of them. https://www.tjernlund.com/airshare_ventilation.htm

 

[dcg9381]

I have a 16' (eve) shop. I'm planning a 2nd floor over about 25% of it. My plan is to add an additional mini split... What you're suggesting is probably worth trying.