That sounds like the cat clogging problem with stainless cat on the PH - seems to happen to a few with really tall chimneys/strong draft/no ashpan combination. The outside surface of the stainless cat gets covered with fly ash, blocking the openings, at least in part. No ceramic cat available for PH. Obvious attempts at solution with PH: add a damper, add as ash pan. Did your friend fit into this profile? Would be helpful to know. More info we can get to figure out for sure why some, but only a very few, people are having this cat clogging issue with fly ash. Thanks.