Which year and basis?
For property you convert from personal use to rental use, your basis for depreciation is the lesser of your cost (plus improvements) or the fair market value on the date of conversion.
Domestic property classified as Residential Rental Real Estate under MACRS is depreciated over 27.5 years. No exceptions.
Foreign property classified as Residential Rental Real Estate under MACRS is depreciated over 30 years. (If placed in service before 2018, then it's depreciated over 40 years. But I feel like this is a waste of time to mention since you're not asking about property rented prior to 2018.)
Other things are depreciated as covered in appendix B of IRS Publication 946 at https://www.irs.gov/pub/irs-pdf/p946.pdf. For example, a gas hot water heater is depreciated over 20 years, If the property is furnished, the furniture is depreciated over 5 years. (might be 7 years, but if properly classified in the TTX program, the program will "know".)
Take note that any time you remove an asset from service, you have to "account" for the depreciation taken. So breaking everything down has the potential to craete a paperwork nightmare. You sell a piece of furniture? You have to recapture depreciation taken. A piece of furniture is destroyed and you end up tossing it? You can only deduct as a loss that depreciation not yet taken.
Also remember that assets which cost less than $2,500 can be expensed and deducted in the tax year of purchase. There are a few exceptions to that, but not that many that affect a residential rental property owner.
To me, the really weird one is the gas hot water heater. In one pub (don't recall which) it basically says that anything that becomes "a phyiscal part of" the structure is classified the same as the structure and depreciated accordingly. However, in pub 946 appendex B, it clearly states that a "gas" hot water heater is depreciated over 20 years, instead of the 27.5 years for a rental property structure.
A whater heater is generally a part of the plumbing, and there's no question that the plumbing is "a physical part of" the structure. On top of that, since pub 946 specifically states a "gas" whater heater, that would imply (to me) that an electric, wood fired or coal fired water heater is treated differently. Things like this are someone typical with the IRS.
@Carl wrote:
Domestic property classified as Residential Rental Real Estate under MACRS is depreciated over 27.5 years. No exceptions.
There is an exception @Carl; @jubin2004 mentioned that a cost segregation study had been completed.
Cost segregation would include not only furniture, but components such as appliances, roofing, plumbing fixtures, electrical systems, driveways, flooring, et al.