The exhaust, vented into, not up the chimney. At least they put a 90º elbow in there.
Pretty wood return box.
Nice transition for best airflow.
I went upstairs on my way out, and noticed that the plaster was all gone along the chimney in the dining room. He said the paint bubbled and stained, so he ripped it out.
A month later, he hasn't called back to have me fix the venting. I don't know how it worked for 5 years. It was off on a pressure switch code.