a whole-house hot water heater has a life of 27.5 years (an improvement - in Turbotax class I resntal real estate property) and depreciation would automatically be computed using the straight-line method.
table 1.1 of IRS PUB 527
*if you wan t you can use the ADS system (automatically straight line but also a longer life) which would spread the depreciation over 30 years about $2-$3 less per year.
