If it’s an electric water heater and it appears in good shape, you can simply replace the heating elements and thermostats.

Hi Wendy,It might be wise to ask for a written list of items.If they pull the hot water heater, or the thermostat, or the furnace, or the outside A/C Coils, or the exterior door locks you might want to (re-negotiate) with them about those items--or maybe not depending on the age re service life left in them.That will also let you build a punch list of buy items (re supply delivery shortages due to Covid) and maybe pre-buy them.Just my 2 cents.

Since then, it has been ongoing complaints from the wife about noise from the pipes, boiler, thermostat about every 3 weeks.

Paint, Luxury vinyl flooring, drywall repair, automated thermostat, wifi enabled lock for the front door.

Also, a 100 yr old house is likely to have K&T , at least in some areas, if not all over.Dont know how it works in NY, but around here  computers, "smart" refrigerators, wifi thermostats and other gizmos want 3-wire systems.

The tenant emailed us over the weekend that they cannot get the thermostat unlocked. 

Typically they are attached to a light switch style disconnect and they can also have 1 or 2 thermostats wired to them. 

On the day of inspection they sent a person who only took pictures of our home (we were present), never turned on a light, never adjusted the thermostat, did not flip on the garbage disposal or even turn on a faucet.

All is well.Today, around noon I get a message with a photo of the thermostat- it reads 76, set to 68.

or is the thermostat location an issue.