Do you have a fireplace that uses the same chimney ?
And does anything else use the same chimney?
How many chimneys?
Is the chimney lined or just bricks?
If you don't know. Ask someone. Easy enough to find out.
Buy a couple of battery operated carbon monoxide detectors. And place them throughout the house. You don't have to screw them to the ceiling or wall. Just place them on a shelf or table.
Your local hardware store should have some.
or A/mazon
LINK
About $15.00-$25.00