Also take a look at utility costs - if you can separate them out and have tenants pay their own, it's helpful, because they treat the heat and electric use very differently if they are on the hook.  

Even though you may only plan to renovate three rooms, the existing conditions like electrical service, hvac etc may not be up to code.

Already Metered both electricity and water.

Hello,New owner of a 4plex with 60amp electric service.

Or does it include , new Roof, Plumbing, Electrical system upgrade, and central HVAC?

What type of furnace is it (gas,oil,electric)?

Is installing electric baseboard heat with separate thermostats an option?

I'm more familiar with electric. thanks

The owner pays for electricity for Radiant ceiling heat which adds to about 18K/year. 

In addition she took the electric stove(2 mo old) and the refrigerator.