I just installed a big freezer/blast freezer 28' x 85' x 20' high with a 8'x10' sliding door. It has two heated vents in it. one is the dual flap kind and the other one is a kason 1845 vent. both seem to be working. no ice build up on kason but little ice on dual flap style. But problem is the two long walls have blown out on the 85' sides. approx 2". It is butyled,foamed,blue skinned,has thermo breaks. Have installed lots of freezers (only install panels not refrigeration) and never had a problem but the walls have pushed out twice on this freezer. Any ideas why ???