We have a really expensive heating and plumbing company who does the same.

**All of this Info has been gathered before approaching the Owner**Property Info:-Built in 1940's -12 Unit Building 6-(2Br/1Ba) 6-(1Br/1Ba)-Tax Value $1,300,000-Annual Taxes $16,000-Current Rents are ($850 for 2/1) *couldn't find info on (1/1) but it is well below market Value-1920's Renovated Building in the area Rents for ($1,245 2/1) and ($1,045 1/1)-No Property Manager (owner managed)-Owner Pays Water and Utilities-All surrounding Apts. pay for Water/Sewer Only-(A Class Area) with Mixed Use Buildings and Student Living-Walking Distance to University-2 Units currently Not RentedRehab/Needs -(from what I can see)-New HVAC, has Radiator Heating and Window Units-Living Room Floor (Sinking in) on Top Floor Unit -Cracks in Interior Walls/Exterior Brick-New Roof (I'm assuming) Large leak in Top Floor Unit-New Fire Escape Staircases -Updated Electrical-Updated Plumbing (I'm assuming) built in 1940's-Interior UpdatingI know its a lot of Work, but It's in a great area, and there is a ton of room for Value Add.

Baseboard heating in the summer time not so much.

What are the loads in the house: electric baseboard heat; heat pumps; AC units; laundry; other motor loads.I am failing to see why you would need a 400 amp service without a proper load calculation.There is no code restricting the number of sub panels, they only have to have the correct install and protection.If I were in your shoes, I would connect with a licensed and insured electrician and ask for electrical audit. 

We'd be passing through all utility costs to our tenants, so heating/cooling efficiency in that standpoint isn't a concern. 

If you're any more than 0% through the useful life of any of the major systems (heating, roof, etc) you may need to adjust that number accordingly.Same for Vacancy and Repairs.

Back in tech, I majored in Plumbing and Heating and while I excelled at it, my trade just didn't pull me in for a lifetime career.

Does it have central heat and air?  

When I look at an investment rental property I want to make sure it's in a good area so I use crime heat maps and look at the attractions nearby.

It has a large garage I use for storage, but still keep the house heated.