Heater,Glasswell SVCE (BI-42SD,BI-48SD,ICBBI-42SD,
          ICBBI-48SD)
  BI-48SD Use Prior to Serial #4452000 And From
          #4452030 to #4520000.
          From #4452000 to #4452030 And Starting
          With Serial #4520000 See 7041092.
  BI-42SD Use Prior to Serial #4520000
          Starting With #4520000 See 7041092
  NOTE:   For High Humidity Areas See 7040129