That isn't a way to run an efficient business for the agent to make money.

My agent isn't sure and the owners/tenants are non-communicative as they likely don't want the property sold (estate sale from dead grandparent?).   

I would be careful with the broker who sent you this being the portal of communication.  

A new high efficiency boiler isn't a bad investment either.

I would like to know how to work them efficiently. 

Hi BP,As I start to acquire more and more properties, the efficiency of my records of expenses/income/ROI is getting complicated and honestly not as organized as I would like.  

Either way in that situation you make your goal.I had a lender one time tell me they underwrite 50% opex regardless of sellers numbers because if they take it back from the borrower because of default they will not be managing themselves and they also could not run it as efficiently as the previous owner who sold it to their borrower.Underwrite conservatively for standard industry practices.I don't buy anything on the if the (everything goes right) scenario because if it doesn't you are up the creek.   

We negotiated and agreed on a price, and I've communicated with two potential buyers.

I even use Skype and TeamViewer to communicate with clients so I'd highly recommend looking for one of the best with great references that interviews well with you.So look for someone you can connect with that works out for your situation.Feel free to ask here if you have questions

It also means they can streamline a lot of their processes and you don't waste time and money shifting gears between each stage, accommodating schedules, getting accustomed to new people and communication styles, etc.