I was trying to buy and hold it and offered 75k, figuring a rehab budget of around 25K if I added a duct work and new HVAC system (heater/air conditioner), some normal drywall laminating, floor refinishing, and exterior rehab.

I do not plan to have ductwork installed in each apartment and all four apartments are on 200 amp electric service. 

All new appliances, retexture the whole interior of the house, repaint the interior of the house, new light fixtures, new furnace and duct work, and new insulation in the attic.  

Other things are: white fabric ductwork tape, vct tiles (9x9), mastic for the tiles, vermiculite insulation to name a few. 

I also have to replace the existing gravity furnace and have the ductwork removed so that I can have space to finish off the basement. 

I'm reluctant to do mini splits only because it has what seems to be not too old of a furnace and duct work.

Studs are up, siding is all completed on the outside, front and back door is installed, no duct work into that room yet, there are still steps that go down to this new space. 

@Aaron Zimmerman I have owned two homes with forced air, and I have never cleaned the ductwork.

New ductwork (8k)3.

I know on the most recent 19 unit Comed gave us all the data from 2021.But in general, I think if you estimate between $100-$150 per unit per month, which gets you to a similar number @John Warren mentioned.I honestly try to avoid boilers in smaller buildings if possible, just because I always want to add AC and it makes it so much easier if you already have ductwork.