TM 5-3895-374-24-2 Low-High-Low  system  and  the  straight  Oil  Low-High-Low  system for specific adjustment details (pages 14, 16 and 18). Note The oil side operation  can  be  supplied  with either   a   Suntec   or   a   Webster   oil   pump. Refer  to   the   mechanical   operation   for   the specific system for adjustment details. Gas Full Modulation System with Oil Full Modulation System The  Gas  system  uses  an  automatic  diaphragm  or  motorized  gas shutoff valve to control the on/off flow of the gas.  The Oil system employs an oil solenoid valve to control the on/off flow of oil to the oil nozzle.  A modulating motor controls the modulated positioning of   a   butterfly   type   Gas   Proportioning   Valve   while   a   V   ported metering oil valve provides the modulating function in the oil nozzle return line.  The modulating motor also controls the positioning of the   combustion   air   dampers,   through   appropriate   sequencing   - providing low fuel/air input for a smooth low fire start and an infinite number of fuel/air positions between full low and high  fire.    Additional  finite  fuel/air  adjustments  are  provided  when the  optional  Power  Flame  Varicam^TM  characterized  fuel  metering system is used.  (optional). When   firing   Gas   the   oil   metering   valve   will   open   and   close because   it   is   linked   to   the   modulating   motor;   however,   the   oil solenoid shutoff valve remains closed, and so no oil is allowed to flow to the nozzle.  Similarly, when firing Oil, the butterfly gas valve will open and close, because it is linked to the  modulating  motor; however,  the  main  automatic  gas  supply  shutoff  valve  (motorized or  diaphragm  type)  remains  closed,  and  so  no  gas  is  allowed  to flow to the burner head. Refer   to   the   mechanical   operation   of   the   Gas   Full   Modulation system and the Oil  Full  Modulation  system  (pages  14  and  19,  as well   as   page   21   entitled   “Gas/Oil   Linkage   Arrangement   Full Modulation  -  Standard  System”)  for  specific  adjustment  detail.    If supplied, also refer to page 20, covering “Detail and Adjustments on Modulating Varicam^TM Characterized Fuel Metering System.” Burner Start Up and Service Test Equipment Required The following test equipment is required to ensure proper start-up and adjustment of burner equipment to obtain maximum efficiency and reliability of operation. See page 36 for CO2/O2/Excess Air Curves For Any Fuel For Gas For Oil CO2 indicator or O2 analyzer CO indicator Compound vacuum/pressure Stack thermometer U-tube manometer or calibrated gauge 0-30” vacuum/0-30 PSIG Draft gauge or inclined 0-10” and 035” W.C.  pressure 0-400# oil pressure gauge (two manometer gauges required for internal bypass type oil nozzles) Combination volt/ammeter Smoke tester D.C.  microammeter or D.C. voltmeter, as required by Flame Safeguard programmer selection Note: When   firing   gas   fuels,   it   is   possible   to   attain   CO2 readings   that   appear   to   be   acceptable   (i.e.,   8%,   9%, 10%, etc.) while actually producing an unsafe condition.    At  such  CO2  readings,  a  deficiency  of  air will  create  the  formation  of  CO  (carbon  monoxide)  in the flue gases.  Therefore, when firing gas, test for CO to  make  certain  that  the  burner  is  adjusted  so  that  it has an “excess,” rather than a “deficiency,” of air.  CO is a dangerous product of incomplete combustion, and is     associated     with     combustion     inefficiency     and increased fuel cost. 5.  GAS START UP Refer  to  page  21  “General  Start  Up  Procedures  -  All  Fuels”  and Section  3  for  mechanical  operation  detail  of  specific  modes  of burner operation. Combination   Gas/Oil   systems   should   also   refer   to   page   22, “Information   on   Fuel/Air   Modes   of   Operation   for   Combination Gas/Oil Units.” General Information Some  applications  may  require  the  burner  to  function  at  the  low end of its rated capacity.  As a result, the two combustion air inlets may supply more air than is required for efficient combustion.  In such  instances,  it  may  be  desirable  to  operate  the  system  using only one combustion air inlet and one combustion air inlet damper. This may be accomplished by removing cross connecting linkage between  dampers  and  locking  the  unused   damper   in   a   fixed, closed position.  One way of locking the damper is to use a 10-24 machine screw through the hole in the  linkage  arm,  and  drill  and tap the air inlet housing, or use two nuts on the screw and let the screw bear against the air inlet housing. Air diffuser movement (fore and aft) may be necessary to produce the best flame pattern or smoothest operation.  See page 20 “Gas, Oil or Gas/Oil Burner Diffuser Adjustment” for further information. Gas  and  Gas/Oil  burners  for  Scotch  marine  and  other  selected applications   incorporate   a   gas/air   premix   adjustment.      This adjustment is identified by diametrically opposed adjustment knobs on  the  blast  tube.    See  page  20  “Gas  or  Gas/Oil  Burner  Fuel/Air Premix Adjustment” for further information. (page 3-975)