You can probably just go ahead and live in that 5th unit, but I believe whenever you go to refinance it with a bank or what not, the 5th unit will make it require a commercial loan and not residential regardless of what the county records show the property to be. 

I think the key is to find the ones that actually have a strong investor/commercial background.

Approx 5 commercial  properties with total combined value book value 12m .. actual maybe 20-25m?

Commercial or residential property? 

Also wanting to gain more expertise in the residential/commercial real estate field. 

Currently I manage my own SFH portfolio of 7 doors.

For a rule of thumb, replacing a commercial boiler can range anywhere from $20k to $150k, depending on the size, age, and efficiency.

I suspect you spoke to bank employees who weren’t in their commercial lending division and didn’t understand your borrowing request. 

Questions: - Commercial Loan - what are the best terms to target? 

Quote from @John Warren: @Mordechai Chaimovitz cap rates and NOI are commercial real estate terms, and 1-4 units are not really valued in the same way.