So my first season with the 52i and P68 has come to a close. I plan on doing a thorough cleaning of the exhaust piping this week. Both stoves were metal piping with relatively short and accessible runs. I want to know what type of brush I should buy to clean the soot and ash from the venting. I believe the 52i was installed with 4in pipe and the 68i was 3in. Recommendations are appreciated.