The IRS issued final regulations for real and tangible personal property a couple of years ago. They are attempting to plug some gaps that were used previously. These are complex and beyond the scope of this forum.
Having said that, the structural components of a building are depreciated using the same life and method as the building itself. Components of a central heat or air conditioning system (whether in, on or adjacent to the building) are classified as structural components of the building. As such, these should be set up as a new asset and depreciated over 27.5 years.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
