VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
F24700 (October 2001) Page 30 of 68
MAIN BURNER IGNITIONCHECKS
The complete gas burner assembly is located i nside
the heat exchanger casting in the boil er . The
perforated burner head functions as both pil ot and
main gas burner. The inner portion of the perforated
burner head serves as the pilot to light t he main
burner during the trial for i gnition. Once the main
burner lights, the flame enc om passes the entire
perforated burner head and the pilot f lame
extinguishes.
If burner ignition problem s are encountered, perform
the following checks to ensure components are
adjusted properly.
1. Turn power switch ON and allow the boi ler to
fill.
2. Verify " l ow water" and "high pressure" safety
circuits are satisfied.
A. Water Level in boi ler.
1) Approximatel y one v isible inch of
water in the sight glass.
2) Auxiliary LLCO is satisfied.
a. N2 on relay board ON (low water
safety circuit satisfied).
b. LED on auxiliary water level
board ON.
B. High Limit Pressure Switch
1) Zero reading on boiler pressure
gauge.
NOTE: Burner cycles ON at less than or
equal to 8 PSI and OFF at 10 PSI.
NOTE: High Limit Pressure Switch
automatically resets at approx i mately 12
PSI.
C. Press the reset switch to reset the safety
circuits.
NOTE: Hi Pressure and low water lights on
front control panel should be OFF .
1) N3 on relay board ON (high pressure
safety circuit satisfied).
3. Verify bl ower is running and its operation is
quiet.
NOTE: A "noisy" blower rotation m ay
indicate bearing wear and reduce air
pressure output.
A. N12 on relay board ON (120VAC supplied
to the blower).
4. Verify ai r pressure switch is CLOSED.
A. N13 on relay board ON (air pressure
switch CLOSED and condition satisfied) .
B. Pilot gas valve ener gi zed and ignition
sequence starts.
NOTE: If N13 is not ON or Pilot gas valve is
not energized, then check the air pressure
switch setting as outlined under "AIR
PRESSURE SWITCH ADJUSTMENT".
5. Verify 24V A C t o ignition module and pilot
valve.
A. N1 on relay board ON (24VAC is being
supplied for the system).
B. N13 on relay board ON (24VAC is being
supplied to the ignition modul e).
C. N14 & N15 on relay board ON (24VAC is
being supplied to the pilot igni t ion timing
circuit and the pilot v alve.
6. Verify spark and pi lot ignition.
A. If pilot lights, proc eed t o step 7.
B. If sparking occurs but pilot does not l i ght,
then check the pilot pressure setting as
outlined under "GAS PILOT PRESSURE
ADJUSTMENT".
C. If spark i s not occurring:
1) Restart power ON sequence by
"rapidly" turning the power switch
OFF then back ON. A rapid switching
is needed to keep the boiler from
starting automatic blowdown.
2) Remove ignit ion cable boot from the
ignitor rod terminal and chec k ignitor
position in the burner head assembly.
3) Measure distance the ignitor ter minal
extends past the ignitor nut. Distance
should measure approximately 3/4" to
7/8". See diagram 5898 "COMPLETE
BURNER ASSEMBLY" at the end of
this procedure.
NOTE: Touch ignitor term inal only
and not the ceramic insulator.
a. If distanc e i s ok, proceed to step
5) below and perform step "a"
and "b" then continue with step
"6)".
b. If distanc e i s other than stated,
loosen ignitor nut, set the ignitor
position and then re-tighten the
ignitor nut.
c. Re-connect ignition cable.
4) Press reset switch to start the igniti on
process.