I have seen only 1 wash with a OHD have a blowdown system and it seems to do ok only issue is that when it did blowdown if the was any tri-foam in the lines or presoak it would be all over the floor and it would mess with the ultrasonics.
It will not allow you to wash in freezing weather. It's more for frost protection and to be used with automatic doors. They have a freeze protection system that works with a floor heat system.