A replacement is two jobs in one visit. The new unit goes in, and the old one comes out. The removal has its own steps, its own paperwork, and its own questions. Most of the surprises on installation day come from the removal, so walk it before the crew arrives.
Confirm who isolates the old unit
Before anything is lifted, the old system has to be disconnected from power, fuel, and water where those apply. Ask the installer to say in writing which of those steps they perform and which the homeowner or a separate trade performs. Electrical disconnects, gas shutoffs, and water valves each need a clear owner. If the answer is that someone else will do it, get that person's name and the day they will come.
Ask how refrigerant and fluids leave the house
A cooling unit or heat pump holds refrigerant. Ask the installer how that charge is recovered before the lines are cut, what equipment they use, and what written record they keep. A boiler or furnace has water, fluid, or fuel passages that need the same kind of plan. The answer should be specific. An answer like 'we handle it' tells you nothing you can check.
Measure the exit route, not just the entry
Most crews measure the new unit against the opening it will enter. Walk the old unit's route out as well. Check the doorway, the stair turns, the landing, the hallway pinch points, and any ceiling or attic hatch. Note where the old unit has to be tilted, lowered, or passed through a window. Ask whether it will be carried out or whether a section of wall, railing, or fence has to come off, and who restores it.
Photograph the data plate before it leaves
The data plate on the old unit records its model and serial information. Photograph it before removal, and write down the install year if you know it. Once the unit is hauled away, that plate may be hard to read again, and the photograph is the record that ties the house to the age of the equipment it held. Keep it with the paperwork for the new unit.
Settle the hauling and the leftovers
Ask whether hauling and disposal are in the written scope, and ask where the old unit goes. Then walk the leftovers. Look for the old pad or stand, unused lines and wire, abandoned thermostat wire, an old vent cap, and any cut openings. Each one should have an owner and a line in the scope. If the installer plans to cap a line or seal an opening, ask them to say so in writing before the day.
Walk the empty space at the end
When the old unit is gone and the new one is set, stand where the old one stood. Look at the floor under it, the wall behind it, the clearance on each side, and any scuffs made on the way out. Ask the crew to show you the disconnects they left in place and to point out the shutoffs you now own. Keep the removal notes with the new unit's records.
Questions to put in writing
Ask who isolates the old unit and who restores anything it disturbed. Ask how refrigerant or fluids are handled and what record is kept. Ask whether hauling and disposal are included in the written scope, and where the old unit goes. Ask which leftovers will be removed and which will be capped. Ask when the removal is expected to finish and how the crew will mark the job complete. Anything the answer leaves out should go back to the installer before the crew arrives, not after.
If you are still deciding whether the old unit is near the end of its planning window, the gas furnace page explains how an install year becomes a planning date. The removal walk does not change that date. It only keeps the record intact.