I have a Empire CIBV-20-30 natural gas fireplace I installed in my home. It has 5.5 ft of vertical stack and 19 inches of horizontal stack going through the wall. I used the specified 4" bvent.

When it gets below 35 degrees outside the fire place will not vent. I have tried a horizontal cap, turning the pipe down 45 degrees, 90 degrees, and adding 2 ft of vertical outside. Nothing seems to work. It burns until the temp limit switch shuts it down and no venting happens. When its 40 degrees out or above it vents beautifully.

Any suggestions?



Gas , oil, and wood need air( oxygen) to burn , then the flue gas can be vented. So , let in some air, A K A -open a window. When I lived in a colder climate , I always provided an air inlet , generally a duct pipe from outside to near the furnace, or fireplace in this case. Newer furnaces are generally required to have an ejector fan on the exhaust vent because newer houses are well sealed and it is difficult for a natural draft to work. The lower the outside temperature , the more the problem.

  • I did try cracking a window open. It didnt seem to help. The air intake is fixed from the factory. I also tried cracking the front door open. Also did not help. Maybe a draft inducer on the draft hood will help – Tony Talerico Oct 27 '19 at 18:42

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