@Jordan Lucas Metalworker by trade in the Army; heating and mechanical while I was in high school.If I had to pick a useful military discipline that I have that's transferred/aged well with my real estate ventures, I'd go with both infantry and analyst.

Biggest issue with property is that the heat and hot water are included in rents..

One problem will be I suspect your subs aren’t licensed, as you probably know (it is Miami after all) so they won’t be able to pull the permits. 

The home is older, built in the 1930, radon levels are at 5.5, but it does have gas heat (most are oil in this area), and window units for air. 

The heating and cooling were simple wall units for each door.

In addition to that, I added mini splits in the up stairs and addict  rooms to make heating and cooling way more efficient as well as put up a wall and door for an office on the second floor.

I was once told the pool was heated at an apartment.

The reason I ask this question is because I have found what it seems to be a great deal in Miami.

In my market I need a 2% -3% rule for it to make sense due  to higher property taxes and heating cost.

The units have separate heating systems currently and separate duct work, and each unit is between 1200-1250 sq ft.