flue gas question

bennythepitbull

My b vent does not behave like other flues (say clay liners) in the neighborhood. When my furnace is firing I see nothing coming out of the top. I had a combustion analysis by ugi and all test were good. Is there a reason why some gases are visible in the cold and others are not 

Tim McElwain

All products of combustion that

vent out of the flue are not visible, the only thing that becomes visible is the water vapor which is created in the combustion process. Type "B" double wall pipe has much higher insulating qualities than say a clay tile liner chimney. That is why B vent is better for venting. The B vent takes less time to develop temperature difference called "Delta T" which along with the height of the vent is what creates draft. That may mean many times that no visible vapor can be seen escaping the vent. Wait for a real cold morning and then go look you then may see some vapor or Plume as it is often called.

bennythepitbull

thanks much Tim

thanks much Tim

icesailor

Flue Gas:

Actually, it has a lot to do with the temperature of the flue gas, the amount or moisture in it and the dew point. Your flue gasses could be far different than your neighbors and chimneys with flues have different characteristics than "B" vent.

Tim knows.