I just had the plumber here to replace a zone valve in the heating system. It was beginning to leak so sooner or later it would have blown completely and ... water running down the driveway. I don't know what the boiler would have done. Run continuously filling the garage with steam!?!
Regarding people living alone: one of my good friends had an agreement with a neighbor. If the neighbor woman saw the blinds open in his living room, all was well. If not, then something was wrong. Likewise with her. After not seeing his blinds open, she called the cops. They went in his house and found him dead of a heart attack, sitting on his sofa from the prior night. This happened two years ago and I miss him. 62 years old.