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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
F24700 (October 2001)Page 37 of 68
7. Once the correct pressure has been set, turn
the gas supply and power switch OFF. Replace
the adjustment screw cap and manifold
pressure plug tap plug on the valve.
8. Turn the gas supply on and check for proper
operation.
IGNITION CONTROL MODULE
CHECKS
1. Turn the power switch ON and allow the boiler
to fill.
2. Aux. water level control satisfied and high limit
closed.
3. Press the reset switch.
A. Combustion blower comes on and
generates pressure to close the air
pressure switch contacts.
B. Ignition control module is energized and
trial for ignition starts. Check for 24VAC
between terminals five and six.
C. Ignition module closes the internal pilot
valve contacts. Check for 24 volts
between terminals two and three.
1) High voltage is sent from terminal
nine to the spark electrode and
sparking begins.
2) At the same time, pilot timing circuit
(control board) and pilot valve are
both energized allowing gas flow to
the pilot.
NOTE:
The pilot valve will be energized
by the relay board timer circuit for
approximately 15 seconds to light the
main burner.
D. Pilot ignition is established (pilot lit), and
main gas valve is energized. Check for 24
volts between terminals one and two.
1) Sparking stops.
2) Ignition module monitors main burner
flame.
3) After 15 seconds relay board timer
times out.
a. Pilot valve de-energized.
E. As long as the ignition control module is
sensing a burner flame through the ignition
cable on terminal nine, the internal main
voltage (MV) and pilot (PV) contacts
(N.O.) remain closed.
NOTE:
If pilot flame is not sensed within 15
seconds, you can re-start the ignition
sequence.
F. "Rapidly", turn the power switch OFF then
ON. A rapid switching is needed to keep
the boiler from starting automatic
blowdown. Then press the reset button.
NOTE:
If the power is not re-set, the ignition
module continues sparking for a total of 90
seconds, then locks out. The module remains
locked out until the power switch is turned to
OFF then back ON and the reset switch is
pressed to re-start the ignition trial cycle.
Terminals:
1. Main Valve
- 24VAC will be present on terminal
#1 with the flame sensing electrode sensing an
adequate burner fame. This output voltage will
remain present as long as the burner flame
remains adequate.
2. MV/PV (common).
3. Pilot Valve
- 24VAC will be present on terminal
#3 at the instant an input voltage is supplied to
the module. This output voltage will remain
present on terminal #3 providing an adequate
pilot flame is established within 90 seconds. In
the event that an adequate pilot flame is not
established within 90 seconds this output
voltage will drop out.
4. Ground (burner).
5. 24VAC Neutral (ground).
6. 24VAC Input.
7. High Voltage to spark electrode. Provides high
output voltage (13kv peak) to the spark
electrode to light the gas pilot. Once pilot is lit,
provides a path for flame current sensing by
the Ignition Module via the spark electrode high
voltage cable on terminal #9.