Chimney screened cap with capped liner below

[Jon mackay]

The gas fireplace installed had some back drafting at start-up and some minor scorching.
I was wondering if the scenario in the picture would contribute to that and if it is even allowed.

[Bob Harper]

Looks like a B-vented (single 4" aluminum liner) vented gas insert with an illegal unlisted shroud.

Good catch Jon!

Need to remove shroud, level II, service by qualified gas pro and depressurization testing with combustion analysis.

[Jon mackay]

Thank you Bob.