I'll side with their research and mathematical modeling and not pay them and just pay for repairs/replacements myself. 

Many of the older furnaces are better built with cast iron heat exchanges, versus steel in later models and have no electronics to fail.

When I google Economic vacancy, that appears to basically be the same thing, except it includes things like giving a free month of rent and model units.Is that what you are talking about, or should I be looking at something else?  

Let's do the math - presuming a 50/50 split between the brokerage and agent (my best guess)Their model: a $400,000 home generates $4,000 in gross commissions and $2,000 for the agent.  

The goal of the research was to model secondary and tertiary markets that were similar to areas like Raleigh, NC, Salt Lake City, UT and other secondary/tertiary markets that had seen major growth since the recession; then try to pinpoint where the institutional capital started to emerge. https://1drv.ms/f/s!

In the other, I had a vacant unit in the same building so I let the tenants shuttle their food into that fridge while awaiting delivery of their new one.

In our model, we are assuming refinancing the first two properties after Year 1 by cashing out our initial $1M investment in each, and then reinvesting that $1M into another 30-40 unit complex at a ~$3M price.Basically: Year 1: Two properties at $1M eachYear 2: Refinance both properties, get initial $2M out of each property, and reinvest in another 2 like properties (4 properties at end of Year 2)Year 3: Refinance both recent properties, get initial $2M out of each property, and reinvest in another 2 like properties (6 properties at end of Year 3)Year 4: Refinance both recent properties, get initial $2M out of each property, and reinvest in another 2 like properties (8 properties at end of Year 4)Our model is to do this until Year 10. 

There may be one-offs but that is not a business model. 

I am a big advocate of modeling the teachings.

Have the post office stop all mail delivery.