Week three…this is a New England classic. So many homes in the northern US predate oil and gas heating and have (or had) wood heating. Chimneys were basically a giant, centrally located thermal mass that helped warm the building.
We’ve seen some of the problems with the framing around the chimney. Here’s a photo inside a chimney. This one was unused and did not have a working damper. It was a wide open 2 square foot hole, open year-round. Obvious as hell once the blower door was running, not so much to the naked eye.