"Lisa Gardner" wrote

We want to remodel our kitchen, but a large 9" round chimney vent to
our roof connected to our furnace and hot water heater runs through
one of our cabinets, taking up a fair amount of space. In the
remodel, we are putting in a new wall to separate the kitchen area
from the dining area that is next to the existing chimney.

A handy friend of mine said that I could convert the round pipe to a
rectangle (3 x 10) that could run through the drywall.

Just make sure you have plenty of insurance on the house......