Many smart thermostats say you can install it without power from the furnace, but this just means it's running off batteries.

My first action would be to immedately install sealed ten year lithium battery smoke alarms throughout the property and institute a frequent inspection program to ensure that they are not interfered with.

Though I do believe that long term prospects of oil are rather dim, given the advances in solar power sector (batteries and photovoltaic panels). 

Plumbing issues, oil heat and who is responsible if they let the tank run dry, batteries in smoke and CO detectors....

I missed out on thousands in revenue when I first started by using Airbnb's smart pricing tool-Put a lock box somewhere on the property for when your digital lock runs out of batteries or malfunctionsHope this helps! 

Actually, the most annoying example is the tenant takes the battery out of the smoke detector because it was chirping, which is a violation that has the same result.I will add to this an issue you did not bring up. 

The few hours of work it took to install mine has payed off, with a battery back up the system does not go down even with power outages, they would have to smash my cameras to stop the recording.There may be legal issues though, if you are in a bad area where nefarious acts happen the police could take your system to conduct investigation. 

I also discounted the typical items like missing batteries and light bulbs. 

@Ethan GriffelHere’s what I expect from my tenants:Pay rent in timeKeep the house niceShovel/mow as needed Replace light bulbs and smoke det batteries.

To get better coverage, we put on one of our buildings, then we put a post away from the buildings towards the back.If the battery (lasts about 3 years) runs out, you get a call.