On another note, I was kidding about he at least they have an LLC comment.  

In the last 4.5 years expenses have been roughly $17,000 (replaced all 3 heating systems with tank-less hot water heaters).

Just to add two more elements that may or may not be a major factor.

The winter surge of COVID-19 brutalized much of Los Angeles County (see LA County heat map below), sending case rates and deaths skyrocketing for weeks.

The properties had very under market rent and all the duplexes had new roofs, heating and air systems and windows.

I currently have one gas line/meter feeding 3 forced air heating units and 2 boilers.

In short, and risking being very superficial, it goes like this - you reach a prior agreement on the different elements of the rehab and much each should cost.

Just adjust the rent for the smaller area to cover the free utilities like30-40 percent more.Hopefully all four different tenants will get along with this arrangement.I would be renting to tenants that have a very relaxed mindset forthe heat and air will need to be in a very comfortable arrangementbetween each set.Maybe a blue/red personality for the tenant that pays the utilities anda yellow personality that pays the extra and doesn't get to upset whenthe heat or air is to hot or cold!

My goal was to get a better understanding of what is on sale in the market from a small multi standpoint and get a better idea of what the "quality standard" is for units to compare with my own property.Doing a very quick walk I could tell that there is a lot of work that needs to get done (3 heating system replacements, a leaking water heater, potential foundation issues, new roof needed, etc., etc.)

What I can't figure out is how is he heating all four apartment with just two of these units?