Chimney cap

[fbret]

I'm ready to install a gas insert into my existing wood fireplace. This weekend I went on the roof to check the chimney cap and need help!

The top on the chimney is 4'x2' flashed with sheet metal with the edges folded over the vertical sides (if only I had taken a picture!). At the center, a round sheet metal 18" tube with the cap screwed to it.

I'm assuming I do not want to compromise the integrity of the flashing / tube assembly, so I need to find a collinear chimney cap that is 18" in diameter to screw into the end of the tube?

If so, I'm not finding anything that fits the bill :-(

Thanks

-Fred

 

[DAKSY]

The co-linear insert liner caps are mounted to an 18" SQUARE plate.
That plate is meant to be trimmed & handbrake bent to go down the
sides of a terra cotta chimney flue tile.
What I have done in an install situation like yours is to take a piece of
20 gauge sheet aluminum & cut it to a LARGER square plate - the size
will be determined by the height of the chase top collar - & mounted THAT
to the co-linear cap base plate.That can now be cut & brake bent to allow
you to attach it with zipscrews to either the collar or the chase top.
Liberal amounts of silicon will be needed to leak proof the zipscrew
attachment points.