If you have your 6/8 month cash for emergencies set aside,  your investments are running like well oiled machine, and still have some spare cash,  go talk to a fee only fiduciary financial adviser. 

It allows me the peace of mind in knowing that they are replaced on time and gives me an opportunity to inspect for HVAC issues and head it off before they become emergencies or unplanned expenses.

They are one emergency away from being wiped out. 

Now every thing is cash flowing and I have cash reserve/line of credit set up for emergencies.

But I'm considering those more of an emergency acct.

I will take each months rent and put it into the companies checking account and keep it there, pay bills with it, but let it grow rapidly and get it to the point where i feel this is enough to cover the worst emergency ( usually a roof ). so my SFH up to 3FH i figure to leave 10K in there, then when you reach that steady balance you start to draw the money out.

Lastly,  a line of credit for emergencies that go beyond the ability of the first two sources.  

Just get yourself a decent vendors/handymen who can handle emergencies in that area.. 

It still an emerging market.  

When an A/C unit stops working tenants will make this an urgent emergency.