Hello i had a roof leak and had to remove the wall behind my pellet stove, i was shocked to see how it had been installed. Im in need of some info on how it should be what rating pipe to use and how to run through my existing chimney as its not correct now with the red duct tape. Seems like the vent is single wall flex and doesnt seem kike a good idea. Even the tape around were it connected to stove melted. Glad we found this when we did. Thank you. Please help