I have two schwank radiant tube heaters in my shop for 2 years now both are two stage burners the tubes closest to the burners are aluminized steel are fine with no surface rust. But tubes at ends non aluminized have lots of rust that falls off like powder on cars and equipment otherwise i love the heat any one else have this happen? Shop is heated at 60 degrees all winter and air-conditioned all summer so should be low humidity. Shop is insulated with open cell foam.
