5.5" round vs. 5.5" x 7" oval flex liners - any clear winner?

woodpile Posted By woodpile, Dec 16, 2005 at 8:15 AM

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  1. woodpile

    Member 2.

    Dec 6, 2005
    This is for a Lopi Answer. A 6" will not make it in my 6.5 x 10.5" clay flue.

    Code comes first.
    The village people say it must be installed as per the instructions. the instructions only imply a 6" flue is needed for installation in an existing masonry fireplace. For a factory built chimney, they say 6". For an insert with a face seal or in a zero-clearance FP, 28 - 144 sq inches. So they come pretty close to saying 6" (6" = 28 sq in).

    Draft comes second.
    Lots of arguments have been batted around about whether an oval is as efficient for producing draft as a circle. I don't know, and all I can imagine is area and drag. The Answer is about the smallest stove, so I do not imagine it is about capacity.

    Installation comes third.
    I would imagine that the round is more flexible than the oval. The oval will also need to be made round again at the ends. The 5.5" round needs to be adapted to the 6" stove outlet.

    Cost comes fourth.
    It will cost about an extra $160 to have the 6" ovalized & shipped freight.


  2. elkimmeg

    Guest 2.

    steve the 5.5/7 meets or exceeds the area requirement therefore it should be ok. The 5.5 round does not, though probably will work
    This is a constant problem and question I deal with all to often. I have passed the 5.5 round application if there is enought verticle length exceeding the minium required by 25% Meaning if 15' is required I pass it in chimnys 20' or taller. I also have to factor in the friction of the 90 degree bend and may require it to be used only in a taller application around 25 verticle feet
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