We have an issue where smoke from the fireplace is getting sucked back in another unused flue into the basement. After trial an error I discovered that it was being cause by negative pressure, I can fix it by opening a window in the basement 3 to 4 inches. When the window is opening the draft stops coming into the unused flue.
I had an HVAC contractor come out and he gave us a solution to install a 6" fresh air pressure relief duct work with a barometric backdraft damper. He proposed ducting this from the outside directly into the cold air return of the furnace. He then said when we have a fire to turn on the fan to circulate air.
My question is when this relief valve opens and brings cold air directly into the cold air return and the furnace isn't running won't this just circulate cold air throughout the house? Shouldn't it be brought thru some kind of heat exchanger first then dumped into the cold air?
I purposed this question to him and he suggested turning on the furnace fan when having a fire to circulate the warm air from the fire to mix with the cold air that the relief valve is letting in. Just doesn't sound right to me that the heat form the fire is enough to counter act the cold midwest air.
Does this sound correct? Quote of material below.
Install 6" fresh air pressure relief duct work, Includes galvanized wall hood with screen, barometric backdraft damper, 6" pipe and fittings, R-8 insulation, materials and labor.