Hello BP,My rental is a single family home that I'd like to upgrade with a nest thermostat.

Hello,I recently closed on a triplex and the apartments feels very chilly in winter weather proofing with a plastic cover sealing the windows  mitigated the issue little bit but I would like to get to the root of cause since even when thermostat is set at 80 it feels chilly,especially my lower two units are very cold despite a centralized ac system.Unfortunately I couldn't catch this during inspections since it was warmer weather around that time.I am now dealing with higher utility bills who are some professionals that I can get in touch with for solid weather proofing ?

The floors were extremely unleveled and the new flooring was already coming apart, in one unit a previous landlord spray textured over every surface of the property including the thermostat/door knobs/trim, in both units the kitchen and bathrooms were falling apart and barely above usable condition, the staircase in one unit was obviously illegal it was so steep, and the walls/ceilings in both units were a mixture of poorly cobbled together panels, cracked lathe & plaster, suspended ceilings that should have been replaced a decade ago, and entire surfaces made from something I couldn't determine.  

If they set the thermostat at 70 then its their choice, but I have never had even close to that high a bill winter or summer 2800 sq ft.

I would assume there would be problems if only one tenant is controlling the thermostat.

Most of the old systems  put the pipes in direct contact with the cement.There is also the possibility of installing electric in wall heaters with fans and thermostat.

I have no idea.He also wanted to throw in a new thermostat "at cost and no labor" for $40.

Most of the requests are minor (sink is plugged, thermostat isn't working), there are just a lot more than I planned on.Maybe 14% is the right number.  

Hard living was the term used by our insurance company; entire house carpet had to be replaced (see image and imagine 1700 sq feet of that), walls & doors were used as children's personal canvas which resulted in repainting & staining of entire house, closet doors were off &/or damaged, siding was hanging off of the outside of the house in several places, thermostat removed, gas meter removed due to illegal gas consumption, drawer/door hardware missing or damaged, damage to garage doors, etc.

The heater will produce the same amount of heat, whether there's an extra vent in the hallway or not, because it will react to the temperature in the room where the thermostat is and that would not be changed by that extra vent.