We currently have a *water conditioner" instead of a softener so we can't just use the red-out salt, which works in my area.Anyway, I'd like a basically maintenance free type filter and there seems to be several kinds.  

I am willing to offer water and most electricity at no extra charge, but I'd like to put something in the lease that requires payment towards oil and air conditioner usage over a certain point. 

We just acquired a property in suburban Portland OR where almost half the tenants had bought and installed window air conditioners (with various amounts of skill).

I am considering replacing a split system air conditioner/furnace in a 1000 sq. ft. 3/1 rental home with a new 2 ton AC unit and a 70k BTU gas furnace.

Its going to be a simple buy and hold.One partner has an extra air conditioner that he is donating, the other is a firefighter who wants to spend time working on an investment.

I have seen Chinese drywall destroy some air conditioners, quickly.  

:mrgreen: According to my maintenance guy they are going to get a new air conditioner this summer, because he feels that my current unit is about to die.

Also keep in mind that major expenses will happen eventually like a roof or air conditioner.

I assume  you're referring to central AC, and not just window air conditioners?  

Just make sure to set it aside big chunk of money so when a roof or air conditioner needs to be replaced you have the $5,000 to $10,000 to do that.