Most homeowners picture an install as hardware: the tank on its pad, the lines connected, the salt poured in. The setting that decides whether the softener does its job is a number entered into the control head near the end of the visit, and it is easy to let it slide past. Before the tech packs up, you should know what number went in, where it came from, and who will change it later.
Where the number came from
Hardness is measured in the water your house actually receives. A careful installer tests the supply at your home, or uses a result from a test taken at your tap, and writes that result down. A number carried over from a different house, a neighbor's unit, or an old label is a guess. Ask what test was used and get the result on the install paperwork. If the answer is that the setting came from a general table with no test, ask why, and ask whether they will retest the water after the unit has been running for a while.
What the control head needs
Three values usually decide how the unit behaves: the hardness setting, the regeneration timing, and the capacity figure tied to the resin and the salt. Ask the tech to read each one aloud from the display and show you where it is recorded. Then check how the regeneration is triggered. A clock-based schedule runs at set times whether or not much water was used. A volume-based schedule waits until a set amount of water has passed through. Ask which one was chosen and why. Also ask what time of night the cycle is scheduled for. A regeneration that starts during the morning shower is a complaint waiting to happen, so the cycle should be set for an hour when nobody is drawing water.
Check the bypass before the truck leaves
Confirm the bypass valve is in service position and that water is passing through the softener to your taps. This is the one setting that can leave you with hard water at every fixture while everything else looks finished. Turn on a cold tap and a hot tap yourself, and make sure the water runs without the tech having to explain why it doesn't.
Ask what changes the setting later
Settings change when the household changes, when the water supply changes, or when a repair resets the control head. Ask three things: who is allowed to change the number, whether a service visit can reset the control head to factory defaults, and what you should keep on record. A short note on paper, or in whatever record you keep, showing the hardness result, the setting, the regeneration plan, and when it was set lets the next technician start from facts instead of the factory default.
Put the setting process in your comparison
An installer who tests the water on site, writes the result down, reads the settings back to you, and explains the regeneration schedule is showing you the work. One who says the unit is set and shows you nothing is asking you to trust them. Ask every company on your shortlist the same three questions: what test sets the hardness number, how will I see the settings on paper, and who changes them later. The answers will separate companies more clearly than the brand on the truck.