The same day my property manager arrived to show the property to a potential renter (difficult to rent in January) to find the house “quite cold”.When she went to check the heat the thermostat had been ripped from the wall.

Z Wave thermostats, locks and the like can help automate the check-in and monitoring processes.Read up on this forum.

Specifically this situation involves a tenant that will turn down the thermostat to our buildings boiler, in the winter season if she feels that her unit is too warm.

Ignition switch failed, house temp had dropped to 38 when we disciovered it on our honeywell thermostat. 

Another option is to install heat tape and a thermostatic control.

I will replace my pipes with PEX, properly insulate pipes, have the thermostat set to a certain temperature when a property is vacant, require tenants to have renters insurance, and send a reminder to keep water dripping in cold temperatures. lol is it odd that I am actually excited about working on this project instead of experiencing sleepless nights (*knocks on wood) ...

Patronize some of the tenants and see if you see water stains on the ceilings, take a look at their thermostats to see if they look like they're from the 80's, see if you see fire suppression systems, look at the parking lot condition, outdoor lights (if they are still the metal halide then you'll want to replace them with LED). 

A friend had mentioned installing a thermostat by Honeywell that has 4 - 6 sensors that report back to the thermostat to then try and average the units and come up with the appropriate thermostat setting to keep all units where they should be.

I also have the Nest thermostat

@Justin BrickmanMy recommendation would be to get WiFi thermostats and control the temperature remotely.Depending on state solar does not provide a significant ROI