The flip side is that there are more expenses with a multi-family property, such as water/sewer/trash (can be billed back to tenants on new leases), landscaping, maintenance, and capex x4 units (4 air-conditioners, 4 hot water heaters, 4 kitchens, 4-8 bathrooms, etc).

The house ended up having a newer air conditioner unit that was never permitted, $, after the fact permitting and bringing up to code. 

Replacing an air conditioner could cost you 3 years of cash flow to recover.

I purchased a new air conditioner for my primary residence in the summer of this year.

A heat pump would have the added bonus of doubling as an air conditioner in the summer {vitally important in a big old Vicky with no insulation}.

Section 1 items to be cleared and any Section 2 items that may be a health and safety issue are also to be cleared, otherwise property is ineligible for financing.and...10. 1004D: WATER HEATER DOUBLE STRAPPED IN UNIT C/AIR CONDITIONER FASTENED IN WINDOW IN UNTI C OR REMOVE AS WINDOW DOES NOT CLOSE / FLOORING INSTALLED IN BEDROOM IN UNIT C, MOLD REPAIRED IN UNIT D.

I'll confess that my level of sympathy is pretty slim when an air conditioner has broken in the heat of summer, and it will be 2 days before the repairman can get there.

In my case I have 4 air conditioners, 4 stoves, 4 refrigerators, etc.

Heck in the Vegas summers, we turn off the air conditioner and open the windows and the heat it that way (kidding).

Would it be most efficient to replace with forced air furnace and air conditioner?