jetsam
Minister of Fire
You need to sweep as often as you need to sweep. You won't know unless you look. The worst part is usually near the top where it is coldest, and the worst times of year are fall and spring when it is warm out (because you burn lower then).
Get up there and at least look into the flue with a flashlight once a week at first. You will quickly get a handle on how often you actually need to inspect and sweep. Remember that it gets worse when you use wetter fuel and when you run the stove lower, so whatever you are doing in the winter may not be enough in the spring.
With my setup, sweeping does not take much more time than inspecting, so I just sweep every time I go up there whether or not it looks like it needs it.
Get up there and at least look into the flue with a flashlight once a week at first. You will quickly get a handle on how often you actually need to inspect and sweep. Remember that it gets worse when you use wetter fuel and when you run the stove lower, so whatever you are doing in the winter may not be enough in the spring.
With my setup, sweeping does not take much more time than inspecting, so I just sweep every time I go up there whether or not it looks like it needs it.