10 Unit Apt Building. Treatment of replacing HVAC unites

I apologize in advance for this but for some reason I find the depreciation rules, Bonus, and Sec. 179 difficult!
We own an apartment building (residential rental) in Florida with 10 units and I'm super active and busy managing it.  I must replace 5 HVAC units.
I have always thought that HVAC units were part of the building (real property) such that replacement of them must be capitalized and depreciated over 27.5 years.

These authors here seem differ with this conclusion saying that Bonus rules and Sec. 179 are available:


"Section 179 HVAC Deduction for Residential Rental Property"
https://accountinginsights.org/section-179-hvac-deduction-for-residential-rental-property/

 

"Bonus Depreciation Saves Property Managers Money"
Learn what bonus depreciation actually means for property managers, what qualifies for a deduction, and the easiest way to start saving. (See the chart "Personal Property that qualifes for Bonus Depreciation")
https://www.buildium.com/blog/bonus-depreciation-for-property-managers/ 

 

Are they wrong?  Thoughts?