Heater ducts Heater ducts available in our silicone coated material or high temperature canvas. To be used with any portable heater in lengths of 12â??(3.66m) or 25â??(7.62m). Adapter available to accommodate 8â?� outputs. O51 20oz/sq yd 1200F(650C) P51 17oz /sq yd 1000F(550C)