Water-heater Replacement - Expense or Depreciate?

Replaced a water heater for around $4500 in 2020. I've been renting part of my house and been depreciating its value. Wondering if I should depreciate it or add it to this year's expenses. 

 

Wondering if anyone can tell me the advantages of one versus another. One problem with depreciating it is that it will be over 27.5 years, and I will replace the heater in 10 years, so I will still be depreciating it after I replace it, which will be kinda weird. With an expense, I can finish it off this year. Is there any advantage of depreciating it?

 

Thanks!