OK we just got our stove in the middle of last winter. I decided to keep 2 of my unused back bedroom doors shut and let those rooms stay cold. We started burning regular again this year in the beginning of Nov. Daughter came to stay with us over Thanksgiving and I went in to one of the cold rooms to give it a good cleaning before she arrived. I discovered mold on the oak sills of my windows and that REALLY upset me. I went into the other cold room and even found mold on a beautiful leather recliner in there! Grandma always kept her unused bedrooms shut so I did too, but no more!