If I breakdown the heater replacement into heater cost, install cost and miscellaneous costs - each component is less than $2500.
Typically, that's not done. Per IRS Publication 946:
The basis of property you buy is its cost plus amounts you paid for items such as sales tax (see Exception below), freight charges, and installation and testing fees. The cost includes the amount you pay in cash, debt obligations, other property, or services.
Exception. You can elect to deduct state and local general sales taxes instead of state and local income taxes as an itemized deduction on Schedule A (Form 1040). If you make that choice, you cannot include those sales taxes as part of your cost basis.
