TM 5-3895-374-24-2 17. For Low/High/Off burners · adjust the main gas pressure regulator   in   combination   with   the   air   damper   linkage operation to achieve 8 1/2 to 10% CO2 and 0% CO at the full high fire input rate position.  Make certain the linkage operates  smoothly  and  without  binding  or  overtravel  of the air damper stops. 18. For    Low/High/Low    burners    -    adjust    the    main    gas pressure  regulator  in  combination  with  the  air  damper linkage operation to achieve 81 to 10% CO2 and 0% CO at the full high fire input rate position.  Make certain the linkage operates of  the  air  damper  stops.    Run  burner  to  the  low  fire position  and  lock  motorized  gas  valve  internal  low  fire adjustment to a setting that will attain 7 to 9% CO2 and 0% CO at the desired low fire input rate. 19. Intermittently operate the burner until the  water  is  warm in the boiler, or follow specific initial firing recommendations    provided    by    the    heat    exchanger manufacturer. 20. See items 31 through 35 in this section for recommended limit    control    and    other    control    devices    operational checkout. Burners Designed for Full Modulation Operation After   completing   pilot   adjustments   and   other   procedures   as appropriate in items 1 through 15 above, proceed with modulating adjustments as follows: 21. Initial   adjustments   should   be   made   at   the   low   fire position.  All Power Flame burners are factory tested and adjusted.      However,   to   determine   that   the   metering butterfly valve is, in fact, in the low fire position, observe the end of the metering valve shaft.  The slot in the end of the shaft indicates the position of the valve.  When the slot is in the horizontal position (parallel with the gas flow direction), the valve is fully open.  Refer to page 21, Fig. 28 for  linkage  adjustment  information  and  page  20,  Fig. 27    for    adjustment    information    on    the    Varicam^TM characterized fuel metering system. 22. Turn the burner on and let it advance to the main flame light  off  position.    Take  action  as  necessary  to  hold  the linkage   at   the   low   fire   position   by   using   a   manual potentiometer or electrically disconnecting the modulating  motor.    Power  Flame  burners  are  tested  at the  factory  and  linkage  adjustments  for  modulation  are made at that time.  Note that the factory settings relate to good   operation   while   firing   into   open   test   pits,   and therefore   will   normally   not   relate   directly   to   absolute fuel/air  ratios  while  firing  under  specific  field  conditions. It  is  suggested  that  the  factory  settings  be  noted  and marked   on   the   linkage   prior   to   proceeding   with   final adjustment.      In   this   manner   those   settings   can   be restored as initial reference points, if need be. 23. With  the  burner  in  the  “factory  set”  low  fire  position, adjust  air  and  fuel  linkage  to  good  fuel/air  ratio  low  fire settings (7 - 9% CO2, 0% CO).  Mark the linkage at the new settings. 24. Increase  the  firing  rate  to  the  midway  point.    Set  the fuel/air ratios to achieve good combustion values (7 - 9% CO2, 0% CO).  Mark the linkage as a reference point for this new mid fire position. 25. Increase the rate to high fire position and repeat the test done for the mid point adjustment.  Results should range in   the   area   of   81   to   10%   CO2,   with   0%   CO.      The metering device setting and air damper openings should be marked and noted to obtain high fire reference points. It  should  be  noted  that  an  additional  point  of  the  fire adjustment   may   be   smoothly   and   without   binding   or overtravel obtained    by    modifying    the    regulated    gas    pressure delivered  to  the  burner  metering  device.    The  burner pressure regulator is used to obtain this adjustment and can  be  used  within  available  pressure  limits  to  obtain optimum firing conditions. 26. Operate  the  modulating   lever   arm   on   the   modulating motor  through  the  three  previously  referenced  points. Minor  setting  modifications  may  be  required  to  ensure that the reference points are acquired. 27. Tighten (finger tight) the hex bolt to the linkage rod at the swivel on the modulating motor driver arms and run  the motor through its full travel to ensure that the linkage is “free”  and  that  limits  on  the  metering  device  and  air dampers   are   not   exceeded.   28.      Determine   that   the required gas input rate is being achieved by clocking the gas  flow  at  the  gas  meter.    The  gas  utility  should  be consulted  to  determine  if  any  correction  factors  have  to be  applied  to  the  indicated  meter  flow  rates.    Refer  to page  36  for  additional  combustion  analysis  information and to page 6 for additional firing rate information. 29. Intermittently operate the burner until the  water  is  warm in the boiler, or follow specific initial firing recommendations    provided    by    the    heat    exchanger manufacturer. 30. Tighten all linkages and permanently mark settings. 31. Limit control check should be made as follows: A) Permit  the  burner  to  run  until  the  limit  control settings have been reached. B) The    burner    should    turn    off    when    the    set temperature or pressure has been reached.  If the burner  is  Low/High/Low  or  Modulating,  set  the controls so  that  the  burner  will  go  to  the  low  fire position before the operating limit control turns the burner off. C) After  a  differential  pressure  or  temperature  drop, the burner should restart automatically. D) With  the  unit  running  normally,  open  the  blow down valve and remove water to the point below the   Low   Water   Cut   Off   Setting.      The   burner should turn off and restart automatically when the proper  water  level  is  re-established.    (If  manual reset type LWCO is used, it will have to be reset.) (page 3 - 977)