I have a gas fireplace with ceramic logs. There is a flue in the stack which I can easily open. On the outside of the house about three feet up from the ground is what I would call a dryer type vent. This is the kind that opens when the dryer is on due to the exhaust air flow. I was told that this is for fresh air intake. Two questions: 1) does that sound right?; 2) should it be a different type of vent cover?