Adding a wall vent connected to utility room exhaust
We have a finished basement which is divided into two rooms. One room is my home office which has no venting apart from a ceiling air(in) vent from the heating/cooling unit. This room (about 50 sqft) is next to the utility room and I'm looking to add a wall extractor fan to pull out the old air. In the utility room there is what looks to be a 6 inch pipe that runs up alongside the furnace and to the outside. The pipe seems to be an empty ventilation pipe.
The idea is to connect a wall extractor fan in my office to this air vent using some flexible duct. However since the end of the vent in the utility room is open, I dont want the air pushing back into the house (circulating in the basement). How can I resolve this?
Some thoughts would be to connect an internal fan into the duct in the utility room that turns on the same time as the extractor fan, thus preventing any air pushback into the house. I'm not sure if there is a valve of some kind that could go into the duct that stays open, but closes when there is reverse air.
I dont want to tamper too much with the exhaust fan as I'm sure it is there for a reason. Any thoughts, ideas and suggestions would be much appreciated.