Gently let them know that if they continue to use the HVAC in this manner and it causes the unit to fail, they will be responsible for replacing it due to negligence. 

It is fine to take a gentle approach when talking to them, but those provisions are in your lease for a reason.

Bringing the $750 Tenant to the Real WorldAs for your tenant enjoying their $750-a-month sweet deal, it's time for a gentle reality check.

Contrast that to the bond market--the source of movement for all manner of interest rates--which frequently moves more than 8 times in any given second.In other words, the financial market is able to make its move well in advance of the Fed and that's a substantial part of the explanation for the drop in mortgage rates seen over the past year.

The market is efficient so where illegal immigrants are will causing housing prices to go up which will cause the efficient movement of people to less expensive housing which will cause that housing to go up which will then push people out again. 

And they are being very kind and gentle with their thoughts etc..

Recently started a new chapter in my life and just found bigger pockets, building passive income and the FIRE movement.

Good tenants in these multi-family are the best sources, they know every movement and let me know of negative activity first in many cases. 

It takes $14-20k per year to participate fully in datasources for most markets plus hours per week to see all the listings and movement.

Super rookie here so be gentle...I am exploring the option for a possible rent-to-own situation.