Guess I have to make it a point to stick to a Spring/Fall schedule.
I don't remember, think it was at least a year. Gonna pick out a spot near the boiler to keep a little notepad where I can write the date down.
There was about 4" of fly ash inside the compartment in the back of the base. The ten fire tubes were quite fuzzy inside too.
5 years in service as of December 20th.