I hope this is an easy question. I have a wood burning stove as primary heat and most of the heat rises into this high vaulted ceiling on the 2nd floor. I've put a vent fan in the ceiling there and hooked it , via the attic, w/ 25 ft fiberglass insulated 6" flex to an oval in wall ( not insultated but not in the attic ) in an attempt to move some very warm air into the ceiling of a cold room on the first floor that just doesn't warm up from the stove. Project completed and I was very disappointed. Seemed like low air flow and colder than expected air. The fan is a 110 CFM bath vent fan recommended to me by the local HVAC place. It's 4" outlet concerned me ,and was thinking 110 CFM isn't enough flow. I thought about upping to a 340 cfm fan , but perhaps that's not my problem, perhaps the type of fan is or something else. Any suggestions ? This simple project is starting to get out of hand.