TM 5-3895-374-24-2 32. 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    the    differential    pressure    or    temperature drop, the burner should start automatically. D) With  the  unit  running  normally,  open  the  blow- down valve and remove  water  to  the  point  below the  low  water  cutoff  setting.    The  burner  should turn off and restart automatically when the proper water   level   is   re-established.      (If   manual   reset type  low  water  cutoff  is  used,  it  will  have  to  be reset.) E) Set and check operation of: (1) Low Oil Pressure Switch (if supplied).  Set at  80%  of   low   fire   oil   pressure.      Check visually,  or  test  electrically  to  confirm  that circuit opens at the proper oil pressure. (2) Blower   Combustion   Air   Flow   Switch   (if supplied). (a) Shut burner power off. (b) Disconnect   both   wires   at   the   air   flow switch and temporarily clip them together. Make    sure    that    they    cannot    ground against    anything,    since    they    will    be powered with 110 Volts during the test. (c) Put   a   continuity   meter   across   the   two terminals. (d) Disconnect the wire to the main automatic oil valve. (e) Start the blower motor.  The meter should read  electrical  continuity  as  soon  as  the blower starts. (f) Disconnect the blower motor lead wire, or open  the  main  power  disconnect  switch to the  burner.    Within  4  to  5  seconds  after the   blower   motor   is      de-energized,   the meter   should   indicate   an   open   air   flow switch circuit (no continuity). (g) If   the   switch   does   not   open   in   4   to   5 seconds,  readjust  accordingly.    Turn  the air flow switch adjustment screw clockwise    to    shorten    cut-off    response time,  and  counter-clockwise  to  lengthen cut-off response time. (h) Turn  the  burner  power  off.    Remove  the shorting  clip  from  the  two  disconnected wires and let them hang loose.  (They will be powered with 110 Volts, so  do  not  let them ground out.) (i) Reconnect the wire to the main automatic oil valve.  Turn the burner on. With the air flow switch wires disconnected, the burner  should  go  into  a  purge  cycle,  but neither the ignition nor the main fuel valve circuits   will   be   energized.      If   they   do energize,    there    is    a    wiring    problem. Correct as required. (j) Turn  power  off.    Reconnect  the  air  flow switch    wires    to    the    air    flow    switch terminals.  Place burner back into normal operation. (3) All   burner   and   heat   exchanger   controls and operating devices. 33. The  “Owner's  Operating  Instructions,”  page  43  of  this manual,  should  be  posted  in  a  clearly  visible  location close to the burner. 34. If  the  burner  operation  is  abnormal,  refer  to  Section  7 “Trouble   Shooting   Suggestions,”   as   well   as   trouble shooting information in the flame safeguard manufacturer's bulletin shipped with the burner.  It is also strongly suggested that all test procedures outlined in the flame    safeguard    control    manufacturer's    bulletin    be conducted. 35. Complete   the   “Burner   Start   Up   Information   and   Test Data” sheets on pages 41 and 42. 7  SERVICING AND COMPONENT ADJUSTMENTS General Information on Internal Bypass Oil Nozzle Systems 1. The system is designed to use 300 PSI pressure at the nozzle  inlet  at  low  and  high  fire  (and  throughout  the range   on   modulating   systems).      The   firing   rate   is changed   by   an   adjustable   bypass   arrangement   that allows more or less oil to bypass the nozzle and flow to the   return   line.      Low   fire   pressures   at   the   bypass pressure  test  tee  will  generally  be  from  60  to  100  PSI, with  high  fire  bypass  pressures  from  180  to  225  PSI. These  pressures  will  vary  depending  upon  the  nozzle size  selection  and  specific  job  firing  conditions.    See page  30,  Table  8  for  flow  rates,  sizing  and  pressure information. 2. Smoky fires with apparent large droplet size in the spray pattern are generally caused by low nozzle or return flow pressures.  To properly check the system, it is necessary to verify both nozzle supply and  return  pressures.    Also check   to   make   certain   that   the   nozzle   adapter   and strainer are not partially plugged. 3. Careless cleaning or handling of the nozzle may damage the orifice, causing heavy streaks in the oil spray.  This will also show up as large droplets or sparks in the flame. 4. Off  center  fires,  low  bypass  line  pressures  and  safety lockouts  (due  to  poor  spray  pattern  and  ignition  failure) may  result  from  plugged  slots  in  the  nozzle  distributor head.    When  such  situations  are  observed,  the  nozzle should be removed, disassembled and cleaned. 5. Excessive  “after  squirt”  of  oil  is  caused  by  air  in  the system.  Be sure air is not trapped in pressure  gauges, overhead  oil  lines  or  fittings.    A  leaking  check  valve  on the  bypass  return  line  from  the  nozzle  can  create  the same effect. 6. The   Teflon   seal   should   stay   on   the   nozzle   when servicing.    On  some  sizes  of  burners  using   Delavan 30630 and 30637 Series nozzles, the Teflon seal stays in the  nozzle  adapter.    If  it  is  damaged  through  careless handling, the resulting leak will cause an increase in the burning rate, when the bypass line is closed at high fire. (page 3 - 981)