TM 5-3895-374-24-2 TROUBLE SHOOTING SUGGESTIONS GAS, OIL OR GAS/OIL BURNER GENERAL 1.  Burner Fails to Start A. Defective On/Off or fuel transfer switch.  Replace switch. B. Control circuit has an open control contact.  Check limits, low  water  cutoff,  proof  of  closure  switch  and  others  as applicable. C. Bad   fuse   or   switch   open   on   incoming   power   source. Correct as required. D. Motor overloads tripped.  Reset and correct cause for trip out. E. Flame safeguard control safety switch tripped out.  Reset and determine cause for apparent flame failure. F. Loose  connections  or  faulty  wiring.    Tighten  all  terminal screws   and   consult   wiring   diagram   furnished   with   the burner. G. Frozen oil pump shaft preventing blower motor operation. Replace oil pump. H. Flame  safeguard  control  starting  circuit  blocked  due  to flame relay being energized.  Possible defective scanner- replace.    Possible  defective  amplifier-replace.    Scanner actually  sighting  flame  due  to  leaking  fuel  valve-correct unwanted    flame    cause.        Defective    flame    safeguard control-replace. I. Defective blower motor.  Repair or replace. 2.  Occasional Lockouts for No Apparent Reason A. Gas pilot ignition failure.  Refer to pilot adjustment section and readjust to make  certain  that  ignition is   instant   and   that   flame   signal   readings   are stable    and    above    minimum    values.        Use    a manometer or 0 to 10” W.C.  gas pressure gauge on pilot  test  tee  to  make  certain  that  pressure  is as recommended. B. Check  for  proper  settings  on  direct  spark   oil   ignition electrodes.    Make  certain  that  gap  is  not  too  wide  and that “light-off” oil pressure is as recommended in Section 3. C. Gas pilot ignition and direct spark oil ignition. Verify that there are no cracks in the porcelain and that transformer end and electrode end plug in connections are tight. D. Loose  or  broken  wires.    Check  all  wire  nut  connections and  tighten  all  terminal  screw  connections  in  panel  and elsewhere as appropriate. E. With  flame  safeguard  controls  that  incorporate  the  air flow switch in the non-recycling circuit, ensure that when main  flame  lights,  the  air  flow  switch  is  not  so  critically set as to allow occasional momentary opening of the air switch contacts. F. Occasional low voltage supply.  Have local utility correct. Make certain that the burner control circuit transformer (if supplied) is correct for the voltage being supplied. G. Occasional  low  gas  supply  pressure.    Have  local  utility correct. H. Air  leak  in  oil  suction  line  or  check  valve  not  holding. Correct as required. GAS OPERATION 1.  Burner Motor Runs, but Pilot Does Not Light A. Gas supply to burner shut off-make sure all manual gas supply valves are  open.    Automatic  high  pressure  valve at  meter  such  as  “Sentry”  type  tripped  shut  due  to  high gas pressure-reset valve and correct cause for trip out. B. Pilot solenoid valve not opening-listen and feel for valve actuation.      Solenoid   valve   not   being   powered-check electrical circuitry.   Replace  coil  or  entire  valve  if  coil  is burned out. C. Defective gas pilot regulator-replace. D. Gas pressure too high or too low at pilot orifice.  Check orifice  size  in  gas  pilot  assembly.    Replace  if  incorrect. Refer   to   gas   pilot   adjustments   for   correct   settings. Readjust as required. E. Defective ignition transformer-replace.  Incorrect  ignition electrode   settings-refer   to   gas   pilot   adjustments   for correct settings. F. Defective flame safeguard control or plug in purge timing card.  Replace as required. G. Air  flow  switch  not  making  circuit-check  out  electrically and  correct  pressure  adjustment  on  switch  if  required. Defective  air  flow  switch  replace.    Air  switch  negative pressure   sensing   tube   out   of   position-reposition   as necessary. 2.  Burner Motor Runs  &  Pilot  Lights,  but  Main  Gas  Flame  Is Not Established A. Main shut off or test cock closed.  Check to make certain fully open. B. Pilot   flame   signal   reading   too   low   to   pull   in   flame safeguard relay.  Refer to gas pilot settings section and readjust as required. C. Defective automatic main or auxiliary gas shut off valves. Check  electrical  circuitry  to  valves.    Replace  valves  or correct circuitry as required. D. Main diaphragm shut off valve opening too slowly.  Adjust bleed on valve. E. Defective  flame  safeguard  control  or  plug  in  amplifier. Check and replace as required. F. Butterfly   valve   set   incorrectly   on   modulating   burner. Readjust as required. G. Main   gas   pressure   regulator   atmospheric   vent   line obstructed.  Correct. H. Defective main gas pressure regulator replace. Misadjusted   main   gas   pressure   regulator   -readjust   to meet required operational values. 3.  Carbon Monoxide Readings on Gas Firing A. Flame   impingement   on   “cold”   heat   transfer   surfaces caused  by  excessive  firing  rate.    Reduce  firing  rate  to correct input volume. B. Flame    impingement    on    cold    combustion    chamber surfaces due to undersized combustion chamber.  Refer to  chamber  size  charts,  pages  12  &  13  and/or  contact factory for additional information. C. Incorrect   gas/air   ratios.      Readjust   burner   to   correct CO2/O2  levels  eliminating  all  CO  formation.    See  page 36.  Table 13 for additional information. (page 3-989)