Was that G?A local diver did have a suit heater "fire" up here using 50% as inflation gas about 3 years ago. Its a low frequency but extremely high risk failure. The assumption is there was a kinked nichrome wire in his vest which then smouldered or caught fire. It burned him pretty bad before his suit melted enough to flood (with 40F water) and put it out. After getting 2/3rd degree burns he then had to contend with hypothermia for the remaining 20mins of his deco.