Jotul C450 Liner Sizing Questions

[Mr A]

Can someone help please. I have Jotul C450 Kennebec that I am, getting ready to install. The insert exhaust is 6" round. My existing tera cotta liner is 6" X 15" inside dimension. I need to ovalize, or rectangularize my liner. Since 6" round equals 28 square inch area, , do I need I need my shaped liner to end up with the same amount of exhaust area? One supplier is offering 4" X7-3/4"(24.35 sq,in.) ovalized from 6-1/2" liner= 14% less area. Another supplier has 4" X10" oval(31.4 sq. in.), 10% larger area. Local dealer says they ovalize 6" round all the time, and no complaints. I can get a 4" X 7" rectangular liner, but they say they can't coil it for shipping, and have to ship it length wise for $150.
4 X 10 oval is the best price including connector and cap, just worried it may be too large for the insert.

 

[DAKSY]

I would just get the 6" liner & slightly ovalize it, just
enough to allow you to get it thru the chimney flue.
You'll hafta round it back out to get it into the flex
to rigid adapter in order to connect it to your insert.
When I hafta do this I uncoil the liner & lay it on a
driveway or sidewalk & put about a 3 foot section
of 2x4 on the liner & hit the lumber with a 5lb sledge.
The surface of the 2x4 spreads out the impact & you
don't end up with a series of dents in the liner ....
You don't hafta wail away at it. Just hit it hard enough
to compress it the amount you need, generally 1/2" will
do... Work your way from one end to the other, sliding
the 2x4 along the length. Once you get it down the flue,
you can generally re-round it out with your hands. Just
make sure you wear HEAVY LEATHER gloves. The SS
of the liner is about 1.5 times the thickness of a piece
of toilet paper & will cut you WIDE OPEN, very quickly.

 

[Mr A]

What I'm worried about is the end resulting square inch area of elipsing 6" round. If 6.5" round results in 14% less exhaust area, 6" will be even less exhaust area.

 

[DAKSY]

Your insert will not notice the difference. This is not rocket
science. Ovalize your 6" liner & you will be fine.

 

[robnol]

My installers I believe used a 6x8 oval SS Liner. They used a wooden screw wood clamp to make the oval round to attach to the stove.