Hang on one of the fan blades and have your son turn the fan on its highest speed. I know you must have a really powerful fan in that climate so the momentum should get you up on that shelf in a jiffy.

Seriously, when the builder comes over to fix the detector, have him move it to a more reasonable location or have him sign a lifetime agreement to maintain it as long as you own the house.

Good luck and how is your hearing holding up?