Don’t Underestimate the Danger of Carbon Monoxide
There are many possible sources of carbon monoxide in a home. Unvented cooking appliances, wood burning fireplaces, gas, oil, wood or coal furnaces. Blocked chimneys are another source. So are gas water heaters, gas dryers and tobacco smoke. Carbon monoxide can get in the home if you run your car in the attached garage. Pool/spa heaters, barbecue grills and non-vented space heaters and other wall mounted heaters are sources.
I have actually have seen where people were using gas and charcoal grills in the house. You can’t do this; the fumes have nowhere to vent and are venting carbon monoxide. I have seen non-vented hanging wall heaters in the garage. They have no vent pipe and are venting into the garage, causing carbon monoxide to build up in the garage. As home inspectors, when we run across these heaters, we write it up that the heaters have to be removed.