The estimate to install a new system for furnace and a/c for this unit was estimated at $12k. 

Especially if you have a unique property in which people would want to stay at.

Instead of wasting your money you might want to print out the harmful effect of not replacing the filter for residents and make sure the tenants always get a copy and warning,     Also you can take it a step further and you can-write it in the lease that "if the filters are not replaced regularly tenant understand that this will cause a $300 repair bill at the end of tenancy, where tech or HVAC cleaning co. needs to come out and clean the system."

Mortgage interest calculations are particularly unique.

To my knowledge, I’m the only apartment investor with a major portfolio of properties and who has ever completed an Ironman triathlon, so I’m in a unique position to tell you the following:Apartment investing is way easier!

When the buck stops with you, you’re in a unique position to have your hand on the pulse of a property.My control extended even further.

I found this to be invaluable, because he breaks things into categories and covers the essential pieces in each system. 

Such a large market presents a potentially lucrative opportunity for real estate investors—as long as you understand a few unique characteristics about this demographic.Consider location relative to campus accessibility.

This also includes level above the water table if there is no municipal sewer system available, the lot must be high enough above the water table so the septic system can flow downhill from the house to the tank to the drain field.

Looking for input with any unique conditions anyone has put in their own lease agreements regarding Tennant conduct/responsibilities relating to the property and the other tenants.