You are leaving the house for an extended stretch. The systems keep running while you are gone, so the work is deciding what each one needs before the door closes and who checks it while you are away.
Name the Caretaker Before You Pack
Write down who has a key, who can reach you, and who will walk the house. A neighbor, a relative, or a property service can do the walk. Give that person a written list, not a verbal instruction. A person who has never seen the thermostat cannot be expected to know which setting is the normal one.
Walk the Water
Find the main shutoff and show the caretaker where it is. Decide whether the water stays on or goes off. If it stays on, look at the supply lines to the washer, the dishwasher, the refrigerator icemaker, and the toilet tanks for any sign of wear. If you shut the water off, note which valves are closed and which fixtures are drained. Test the sump pump before you leave by pouring water into the pit and watching it lift and discharge.
Set the Heat and the Cooling
Choose the thermostat setting for the absence and write it on a card beside the thermostat. If the house may drop below freezing, the heat stays on at a low setting, and the owner decides how low. If the boiler or the gas furnace is shut down, label the switch and the shutoff valve so the caretaker does not have to guess. For the central air conditioner, decide whether it runs at a higher setting or is switched off. Confirm that the condensate drain and the outdoor unit still have a clear path. The Gas Furnace guide turns the install year into a planning date, which is worth reading before you choose how long the house sits.
Refrigerator, Disposal, and Washer
If you will be gone for a long time, empty the refrigerator and freezer, unplug the unit, prop the door open, and clean the interior. Leave the disposal dry with the sink stopper open. For the clothes washer, leave the door open so the drum can dry, and close the supply valves if the water is off. The appliances ranked by typical service life page lists the units you are most likely to be checking on return.
Make the Return Walk
When you come back, go through the list in the reverse order you set it. Turn the water on slowly and run each fixture for a short time. Look under every sink for moisture. Start the heater or the furnace and confirm normal operation. Test the sump pump again. Check the thermostat before you change its setting, so you can see what the house was set to. Record anything out of place in a log so the next absence starts from a known state.
The Written Card
Keep one page with the main water shutoff, the gas shutoff, the breaker panel location, the thermostat setting for the absence, the caretaker's phone number, and the order of the walk. Keep the page with your records. It serves the caretaker on the next visit and the next owner who reads the house.