Welcome to the most-common curse of mid-range gas cooktops and ranges.....that is, the difficulty of obtaining consistent low-simmer -- like no boiling over -- without having the burner go out.

I don't know if this unit can be made to maintain low-simmer at a level that will satisfy you but I suspect the unit can be adjusted. If it doesn't appear in the manual (I doubt it) -- or even if it does -- I would go at once to the vendor/installer and ask the question. It is clearly unreasonable to have things boil over on the lowest setting and I would expect them to work with you to make it as good as it can be.

If you pull the control knob off the burner and there is a small screw in the center of the hollow shaft, you can adjust the burner. With the burner lit and on the lowest setting turn the screw until you have a flame that suits you and replace the knob. This may reduce your max output a little, but you don't need to do it to every burner. This is what I did on our old range. There was already one burner that had a low low, but I wanted a second one on the left front. The other 2 I left alone.

Asolo is correct. Despite all the professional style ranges on the market, very few can simmer without cooking/boiling. Wolf, Dacor, and a few others have solved this but it is a feature you pay for.

Just try to visualize a flame small enough to not cook but big enough to not flicker or cut out from air disturbances. Not easy to do.

Easiest fix is to start using a simmer plate or diffuser of some kind.

Caddidaddy55 is is correct. There IS an adjustable screw in the shaft under the knob for that specific purpose. I have a 5 year old model. The instructions are in the manual, but they are exactly as described above.

Admitedly, I have propane, so there could be some difference but I can keep my low settings below boiling on all burners.