Most household breakdowns do not announce themselves. They begin with a sound you stop hearing, a smell you decide is the neighbour's dinner, or a rust stain you keep meaning to check. When you are the person in the house all day, you are the one best placed to catch those signs, which is exactly why they keep slipping past you.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Pick the one system that would hurt most
You cannot watch everything at once. Choose the system whose failure would leave your parent without heat, without hot water, without a working refrigerator, or without a working smoke or carbon monoxide alarm. Those go first. Everything else can wait for a slower week.
Write down what early looks like for that system
For a water heater, the early signs are hot water that takes longer to arrive, a rumbling or popping sound while it heats, rusty water at the tap, or damp spots around the base. For a furnace, watch for short cycles where it starts and stops more often than usual, a burning smell on its first run after a long rest, or rooms that stay uneven in temperature. For a refrigerator, watch for a motor that never seems to rest, food that is warmer than the dial says, or frost forming in places it did not before. Write the sign, the room, and the first time you saw it. One line each is enough.
Keep one log, in one place
Put the list on the same page as the care notes, or in the same phone note. A pattern on paper is easier to act on than a feeling at 2am. When the second and third sign show up, you will not have to argue with yourself about whether it counts.
Ask the service company one question before you need it
Call the company that services the system and ask two things: how a routine check is booked, and which signs they want you to call about right away rather than wait for the next visit. Save that answer with the log. Make sure the other adults in the family know where it is kept.
You are allowed to call before the break becomes a crisis
A routine call is not an overreaction. It is the most practical way to turn a slow problem into a scheduled one. If you keep the log, you can give the technician the history in two sentences instead of rebuilding the story from memory while you are exhausted. For the wider set of questions to bring to the household, the Start Here page lays out where to begin.