Do I have to keep any distance between the hot air outlet on the preheater and the PWB?

When there is not enough space for the hot air to flow out, the temperature fuse will blow.
Please keep the following distance between the hot air outlet and the PWB to allow the air to flow out.
FR-820; 5mm or more gap
FR-830; 10mm or more gap

Setting sample of HAKKO FR-830