I haven't had to clean the glass on my 13NC yet. Just a slight haze in the lower corners. Benefits of getting ahead in the wood supple department.
I can't wait for my wood to season thoroughly. I'm getting decent heat but I know two years from now I'm be doing so much better
When I switched over to the 13, I had window cleaning quite often. Meaning about every 10-12 burns. Now that the wood is nice and dry, I look at the glass and think nice