Exactly what I was thinking, even a small electronic that puts off heat can trick most basic sensors.

Motion sensor lights help too.

Add in water/moisture sensors, etc and you could have a fully-wired house sending you alarms to allow early intervention to what could become major issues.

I repaired both my washer (filter) and dryer (temp sensor) and they lasted 5+ years after my repair.

I worked really hard to cover every base, had the fans upgraded, installed humidistat switch/sensors, increased venting and vans in the laundry area (next to the bathroom), and even bought a de-humidifier to go into the unit as well as reminding my tenants to run the fans, keep the windows open in the bathroom, etc.

We own a digital business card platform called Tendant with a power user version that allows you to build reusable lists of contacts on your phone.

Most companies stake out a place for 20-30 days.Otherwise, you may want to install motion sensors, automatic timers, an alarm system, or cameras (live or fake, but either way a deterrent).  

You would really be looking for something closer to this:https://meetflo.com/how-it-works/Most of the automatic valves out there work off of sensing standing water somewhere, which isn't going to do any good if the line breaks someplace you can't leave a sensor.

We had 3 story 6 plex 100 year old, radiator heat, We had a aqua sensor installed outside the  building by boiler room connected to thermostat.  

I have a canon 70D (crop sensor).