Just about when the cold got colder this month, I noted that the stove was not making the cut keeping the house warm. Our temps at night were single digit with high winds, and daytime highs were in the low 20s. I just could not get the stove to run at it's normal temps. Looked closely at the air flow and found that the main air tube was covered 90% in ash. Cleaned it out, and poof! hot stove again. The only thing I have had to change is the log sizes. The colder temps need smaller, hotter burning logs to keep up. Learnin' everyday.