Duct tape can fix anything except stupid.
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I read the one thing you actually should *not* use duct tape for is ducts.
https://servicechampions.com/blog/why-duct-tape-should-never-be-used-on-ducts/
Cloth duct tape isn't good because the adhesive softens when heated.
Aluminum duct tape is good to use on ducts because it's conformable and the operational temperature range is -40°F to 300°F.
If I ever saw duct tape used in heating or cooling it was to hold together the insulation around the outside of the duct. In other words there was three to five inches of insulation between the tape and the tin of the duct.