VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
F24700 (October 2001)Page 37 of 68
7. Once the correct pr essure has been set, tur n
the gas supply and power switch OFF. Replace
the adjustment screw cap and manifold
pressure plug tap plug on the valv e.
8. Turn the gas supply on and check f or proper
operation.
IGNITION CONTROL MODULECHECKS
1. Turn the power switch ON and all ow the boiler
to fill.
2. Aux. water lev el control satisfied and hi gh limit
closed.
3. Pre ss t he reset switc h.
A. Combustion blower comes on and
generates pressure to close the air
pressure switch contacts.
B. Ignition control module i s energized and
trial for igniti on starts. Check for 24VAC
between terminals fiv e and si x .
C. Ignit i on module closes the internal pil ot
valve contacts. Check f or 24 volts
between terminals two and three.
1) High voltage i s sent f rom terminal
nine to the spark electrode and
sparking begins.
2) At the same time, pilot timing circuit
(control board) and pilot v al ve are
both energized allowing gas flow to
the pilot.
NOTE: The pilot valve will be energized
by the relay board timer circ uit for
approximately 15 seconds to light t he
main burner.
D. Pil ot ignition is established (pilot l it), and
main gas valve i s energi zed. Check for 24
volts between terminals one and two.
1) Sparking stops.
2) Ignition module m onitors main burner
flame.
3) After 15 seconds relay board tim er
times out.
a. Pilot v alve de-energized.
E. As long as the ignition control modul e is
sensing a burner flame through the ignit ion
cable on terminal nine, the i nternal main
voltage (MV) and pilot ( P V ) contacts
(N.O.) remain closed.
NOTE: If pilot f lame is not sensed within 15
seconds, you can re-start the ignition
sequence.
F. "Rapidly", turn the power switch O F F then
ON. A rapid switching is needed to keep
the boiler from starti ng aut omatic
blowdown. Then press the reset button.
NOTE: If the power is not re-set, t he i gnition
module continues sparking for a total of 90
seconds, then locks out. The module remai ns
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 v oltage will
remain present as long as the burner flam e
remains adequate.
2. MV/PV (com mon).
3. Pilot Valve - 24VAC will be present on terminal
#3 at the instant an input volt age is supplied to
the module. This output v ol tage will remain
present on terminal #3 provi di ng an adequate
pilot flame is establi shed within 90 seconds. In
the event that an adequate pilot f lame 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 t o spark el ectrode. Provides high
output voltage (13kv peak ) t o the spark
electrode to light the gas pilot . Once pilot is lit,
provides a path for fl am e current sensing by
the Ignition Module vi a the spark electrode high
voltage cable on termi nal #9.