That way your not just sinking a bunch of money into something that might be close to the end of its life span anyways.

I live in FL so I know about having to use A\C year round.As you know people mention a brand and price but not model which will ultimately determine the total cost.I was in the exact same situation and due to the rusted coil tubing, and overall condition of the Air Handler decided for a total A\C replacement.Payne is considered "Builders Grade" lowest grade and some A\C guys argue not to install them because it reflects on their reputation when you have problems with the system.Look for the highest seer rated, quietest, best warranty HVAC that is fairly priced.The installer is a HUGE part of the HVAC's life span, along with your regular changing filters, cleaning coils when needed, cleaning drain lines and vacuuming dust out of the Air Handler Cabinet.

The updated master list of what has been done to each property, included on my worksheets are repairs as well as expected life span HV/AC, furnaces, hot water heaters, appliances if applicable (assists with my savings budget. 

Research the subdivisions rental activity over 2-4 year span. 2.

Flipping is more money in a shorter time span but over the long term renting will always be more profitable.

We did, and wound up buying three properties (our own SFH, a second SFH nearby, and a 4-plex) in a span of six months.

I schedule one appointment at a time, usually 15 minutes apart over a 2 hour span to minimize the disruption to my current tenant.  

During the rehab, we encountered… a break-in that removed old radiators (fortunately, we were planning to remove them anyhow); a complete failure of the relatively new boiler; a complete failure of the A/C system; rotten floor joists in an existing addition; missing ceiling joists in an existing addition (only 4 joists over a 20’ span); a rotten subroof covered up by 5-10 year old shingles; and more.

We haven't nailed down a specific address yet but the contract spans multiple counties.

You look at a commercial warranty, you will see that it is for 10 years. so I use that as life span.