Replace the copper pipe obviously if you have a leak.Water heaters have two major components, heating element and thermostat.

To top it off, the utilities are connected, so there is only 1 thermostat (in the main house), but the back house has window units and space heaters to regulate temp if needed (the front house is on a schedule and I have a Nest thermostat there that I can control if needed).  

You can manage the door locks, check in check out notifications, thermostat, propane tank levels, calendar and pricing, accounting, lodging tax payments, etc all on your phone.

Wifi thermostats and wifi water heater. 

I use them in my homes for not only alarm, but also for thermostat controls, door locks for each person to get there own door code, lighting controls, and cameras. 

The best one would be to install Nest thermostats(or Ecobee, or some such thermostat) which can be adjusted from anywhere in the world- as long as you have cell service.

My ideas so far-purchase small to medium multi families in metropolitan areas-use "smart" devices like keyless locks and smart thermostats-community space either inside or outside-host community events like BBQ-use online payments methods /maintenance requests Any more thoughts?!

Who controls your thermostats? 

I'd recommend installing a smart thermostat at this point so you can easily track usage from anywhere! 

It sounds like both units are currently serviced by this one boiler, but there is just 1 thermostat (probably in the lower unit).