The utility room has two 8-10 inch ducts running to it from the exterior of the home. There are also three fireplaces in the home, and we have noticed that occasionally the house smells like smoke, despite the flues being closed. Sometimes while starting a fire, the down draft is so strong that the room fills with smoke.
I also believe that when the conditions are right outside, that air drafts down the fireplaces and air from the utility room exits the house via the ducts.
I have checked the ducts and at times there is not cold air coming into the utility room at all even while the gas furnaces are operating, which seems to confirm to me that these ducts are acting bi-directionally at times.
Is there a way to have these ducts perform in one direction only? Providing outside air to the utility room and prohibiting the air flow from reversing?
Thanks in advance!