Short flame for best performance in all applications. fires into long combu...Short flame for best performance in all applications. Fires into long combustion chambers but also into shortest chambers. Increases efficiency. Vacuum mixing method (Patent No. 3589845). Eliminates pulsation or "lifting". Quieter operation, smoother lightoff. Adjustable input with regulator located in the gas valve. Flange or pedestal mounting. U.L. listed with Honeywell or Fireye controls. Controls to meet F.M., I.R.I. (F.I.A.) or special local codes also available.