The software we use on the cabin PC is called Home Domination. It interacts with X-10 as well as other interfaces. I found some inexpensive temperature sensors that are three wire (power, ground and signal) that each have their own serial number and report that along with degrees Fahrenheit. We soldered those directly onto Cat5 cable and have one in the garage (where the boiler is and a lot of exposed water pipes are), on the main thermostat, on the boiler circulator piping and then outside.
My son figured out the internet access (he took Cisco Networks in HS). We use Remote Desktop and can "see" the desktop on the cabin PC and of course access the software. We also have apps for our Android phones.
They do make computer interface thermostats but they are very expensive. So I control the heat by turning on the main thermostat circuit with a low voltage contact on an X-10 device. I have a second thermostat set to 45 degrees to act as a default when the main is deactivated. Once I activate the main thermostat we can watch the temperature sensors report a rise in the boiler temperature up to 180, then a slow rise in the house temperature.
I control the hot water with another X-10 unit that turns on the 120V signal; simple.
The water main was a bit more complex. I wanted to be able to turn that off remotely as I'd always forget to when I left the cabin. So I put a $30 irrigation valve on the line and that worked well until it failed, then we had no water in the house until I took a trip to the hardware store, which at that time was closed 15 minutes before I got there on Saturday and then all day Sunday. So I plumbed in a parallel line with a manual valve and replaced the cheap electric valve with a commercial grade. It turns out that the new electric valve uses 10 watts (electricity is expensive in the mountains) and buzzes. So now I just use the manual valve and use the electric on a simple timer to turn off two hours after I leave (to allow the dishwater to complete a cycle). So I don't forget, I have a paper sign hanging against the windshield of my Jeep where it's parked in the garage, telling me to TURN OFF THE WATER.