Fungal79answered grow question 4 years ago Check your ducting, has no harsh bends.
If you use the duct hole, in the roof of your tent, you will probably end up with at least one 90 degree bend.
I created a new duct hole, on the top corner of one of the tent sides, to overcome this. Maybe not best solution for you.
But making my oulet pipe have no right angles. Instead having a long sweeping bend, dropped my temps by 10c.