The property you use it on will also have to pass a VA Appraisal which is where most at fix and flip's fail.

The heat exchangers fail most frequently on the propane boilers due to the high acidity, low temperatures the propane condensing units run at, my friend who owns a 3rd Generation heating/plumbing company doubts those units will ever come close to outlasting a traditional 3 pass boiler.Agree the pros of having a propane boiler/furnace-fuel is cleaner, services tend to be cheaper, tanks can be bought or fuel company can supply tank, work great if you also have a tankless hot water heater with same fuel source.Efficiency of Maine does offer rebates as well for the high efficiency units, they don't mention this but, if you insulate all baseboard piping that is exposed in the basement, take photos and have a high efficiency oil boiler they will qualify as the same rebate as the propane unit.

The switch is a PITA and a notorious problem with other well owners down here because the switch is outside and exposed to the elements and fireants and frequently fail.

Sometimes the court/bank attorney fails to notify them during the foreclosure.

Many first time flipper really fail to understand that, " time is money". 

My big concerns are some that most sellers have (the Due on Sale clause and what happens if the buyer fails to pay on the mortgage) but I'm also worried about any potential liability to me in terms of tenants that they put in the house.

Unless he fails to deliver on closing by 10/2 the contract is enforceable.  

I’ve been in the mortgage business since 2003 but never turned the corner into investing (aside from a failed primary residence attempt in 06 - perfect timing, I know).

If tenant fails to pay within the 3-day period then the PM can file for the eviction (forcible entry and detainer).

A roof that would need to be replaced “soon” But, I had worked it all out with my personal banker, my accountant and friends and family that won’t let me fail.