is this a bad install

Sloppy, but not enough to classify the install as "bad"
I wouldn't think it would cause a problem...

That really sucks. Why cant folks just take the extra time to do a good job of something? Can you notice it from the ground?

I would send that picture to whoever installed it and complain.

Perhaps prevailing winds come from the direction of the taller side and they did it to improve the draft.
Or they're just hacks....

I would take a close look to make sure the clamp assembly is catching the entire liner and not just the top part showing in the photo. If you don't have a solid connection up top the flex liner could work loose and slide down inside your chimney if there is any tension on the liner. When I installed my liner I made my bottom connection to my stove first and then went on the roof and pulled the slack out of the liner so that it would have some tension on it making it stand up straight and not lean against the sides of the clay tile liner of my chimney. If your flex liner is installed in a similar manner you wouldn't want the top connection to slip loose.

That was cut that way on purpose, flex is a pain to cut without having the right tools, that is not a mangled looking cut. I would call the installer and ask why it was done that way, might be a reason to it. It won't hurt anything being that way.

How is the 450 doing for you? How many sq feet are you heating with it?

Just trim it off.

Personally, I would be more concerned with whatever else they did half assed.


Some, (most) things I don't trust to be "professionally" done anymore.

its hard to find people who take pride in there work ,does it hurt anything ..no but thats not the point .if your gonna do something do it right .

I still say it was purposely cut that way, not a cut rate install. They cut across the ribs which takes quite a bit of pressure and a good sharp blade, looks to me like there is a method to this madness.