@William DavisI can't answer your question, nor can anyone else without knowing the process of accomplishing "a way to minimize your tenant's rent without losing money".I like the sound of "making our air cleaner without switching from gas vehicles" but not if the strategy is killing half the population of people who drive gas vehicles.People are "so quick to judge or make fun of the idea when you don't even know what is" because we don't know what it is and making blanket statements/ asking generic questions and saying "I cant say" when people ask what you're talking about - sounds sketchy.

Our cash-on-cash return would be much less, but we'll still get principal paydown and everything besides the roof should allow us to raise rents (central air, updated appliances, open up the kitchen/livingroom wall, refinish wood floors).

We're in our 70s now and our biggest expenses are for a new Lexus every couple of years and first class air fare.

I'm still up in the air on that one.

@Bryan Clark I'd make sure all the systems and structure are in working order (i.e. roof, plumbing, hot water heater, heating, air conditioning, etc.).

It is a 2/1 near an air force base, in a decent school district.My question is this: how do I run the rental property analysis, how do I account for private money?

Forced air furnace or ac.

@Ryan KurthI'm an HVAC contractor and I have a few, used, warm air furnaces that I keep around for emergency and/or construction use.

Fortunately the smell is reduced enough that just living in the unit provides enough air movement so that it does not smell; for tenant turnover we need to open the unit up prior to the showing otherwise it has some smell. 

I would stick to outer zip codes, not center city zips. 32205, 10, 20, 21 22 44, west of the river. 07,11,77,25,16,46, east of river 18 and 26 by the air port.. if the portfolio is higher end investment homes 17, 23 57,56, 58 59 , and  24 ,33, 66, 50 .toward the ocean.