When you get a new tenant, that’s when the inspection is super important, especially on safety issues with windows, screens, heating, electrical etc…

She says she is nauseous from the heat.

If and when the tenant moves you only need to politely request that nail holes are repaired and walls are painted and that is when you can get a little more-heated up, but the cost to clean up holes made by smoke detector devices is zero to very insignificant because landlords have to clean and paint, anyway.

Complaints about lack of heating and cooling in upstairs new townhouse.

Work needed: NEW ROOF, NEW INTERIOR AND EXTERIOR DOORS, NEW LVT FLOORING THROUGHOUT, TRIMWORK, UPDATED ELECTRICAL PANEL, ELECTRIC BASEBOARD HEAT CONVERTED TO HEAT PUMP (CENTRAL AIR DUCTWORK ALREADY IN PLACE), POSSIBLY A SMALL WALL KNOCKED DOWN, REFRAMING OF CLOSETS, KITCHEN AND 2 FULL BATHS REDONE PRETTY MUCH TOP TO BOTTOM. 

Generally you treat the unit with high heat to kill them all and it is not cheap to get the correct treatment.  

Your best long-term solution is to install the mini-splits for heat/AC. 

Ask the seller about specific items (i.e. heating and air conditioning, hot water heater, plumbing, etc) in these properties and see when they were last serviced and/or replaced. 

In some older homes the water heat vents into the chimney.

AC room by room, and individual heat room by room.