Yes, you can hide your mini-split system behind a piece of furniture. You will want to make sure that there is enough clearance around the mini-split system so that it can properly circulate air. The general rule of thumb is to allow at least six inches of clearance on all sides of the unit. This will ensure that air can circulate freely and that the unit doesn't overheat. It's also a good idea to leave a few inches of space between the floor and the bottom of the furniture piece to prevent dirt and debris from accumulating on the unit.