@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.

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

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.

If you don't know whether or not the owner has redemption rights, that means you don't know if its a judicial or non judicial foreclosure and if you don't know that yet, you probably are premature in your efforts to buy foreclosures without getting a bit more education.7) Yeah?

Never had a premature failure....More important to drain it down every year I think....

Bowles and others stressed that New York City’s obituary has been written prematurely several times, including after Sept. 11, when many feared people would be too worried about another terrorist attack to live in or visit the city.

Or did the lone father prematurely die?

.- Asphalt Roofing Manufacturer's Association "strongly advises caution when considering the application of any type of field applied coating over installed asphalt shingles," due to possible shingle curling/warping and possible vapor barrier may cause premature failure of roof decking.- Some shingle manufacturer's specifically state that coating will void the warranty.