Rafael,It's a little premature to sell now in my opinion.

On the flip side, properties that rent for $1,850 take more time to rent so I don't want to make an enemy of her prematurely.

@Justin Fox - you need to exercise caution with spraying {closed cell} foam directly on the underside of the roof deck as you can both prevent the roof deck from drying (insufficient ventilation) and cause condensation within the roof assembly itself ... leading to premature failure of the roof assembly.

Four months later when we did our property inspections, they had ruined the carpet; there must've been 100 pieces of gum in the carpet.

The buyer or seller for that matter does not get to decide that somehow 3% of that is now theirs to use for a down payment, repairs or to buy trading cards and bubble gum with.Another point is you said "You do not need an agent to buy a primary residence".

@Charlotte AdamsYou've received a lot of advise here, some of which might be excessive or premature for your situation.  

It is very easy to bubble gum a failing roof until it can be replaced. 

Obviously I don't have the properties yet so this is premature but I'm wondering if anybody has experience with either of those strategies to purely build cash flow. 

I am also considering a rent increase because the equipment is used 3x as much and such heavy usage will result in premature failure.

This can lead to additional corrosion w/in the pipes, possibly leading to premature failure of the heat exchanger, which is not inexpensive to fix as I just fixed one on one of my properties.Assuming you're on gas, you could (imo: should) install a condensing gas boiler.