Midco G69B - Manual (Page 11)

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FIGURE 12 Drawer Assembly
If the valve will not open, make sure that normal gas
pressure is available at the valve, the bleed line is
unobstructed, and power is available at the terminals.
If the valve fails to close, make sure power is off at the
terminals and gas flow is in the direction of the arrow on the
valve body. When a malfunction is found to be caused by
the valve operator head, the entire valve must be replaced.
2. Redundant Solenoid Gas Safety Valve
(Required Construction)
Unipower burners feature a redundant solenoid gas safety
valve. This valve is a On-Off (2 position) valve.
When the valve operator is electrically energized, a
plunger lifts the valve disk off the valve seat, allowing gas to
flow. When the current is broken the valve closes. It will
normally require no service. If the operator malfunctions or
the valve leaks replace the entire valve. After replacement
check for leakage.
XIII FLAME SAFEGUARD
WARNING: Explosion hazard. Do not use this
device if it gets wet. It can malfunction and cause
serious injury or death. Replace any device that has
been wet.
Unipower burners are equipped with a flame safeguard
control employing a flame rectification system of flame
detection. The flame safeguard controls function sequence
operation.
For operation characteristics refer to flame safeguard
control literature provided with the burner.
XIV SPECIAL EQUIPMENT (OEM
VERSIONS)
Special equipment, either factory or field installed, can
cause variations in the procedures and descriptions given
in this manual. Generally, any burner ordered with special
factory installed equipment will be supplied with the
appropriate wiring diagram and related instruction manuals
from the special equipment manufacturer. Consult these
manuals to identify any differences in construction,
operation, and testing. Field installed special equipment is
the responsibility of the installing contractor.
For example, when a high/low gas pressure switch is
used, the high gas pressure setting must be higher than
the maximum manifold pressure during initial start-up and
the low pressure setting must be set below the normal
minimum inlet pressure to prevent nuisance shutdowns
during the start-up procedure.
After the burner is started, the low pressure setting
should be raised until the burner shuts off. Reduce the
setting and set the low pressure switch to restart the
burner. Reduce the high pressure setting until the burner
shuts off. Then raise the setting slightly and reset the high
pressure switch to restart the burner. Do not make the
adjustments too close to trip points or nuisance shut
downs may occur. Any time the burner gas supply is shut
off with the main manual valve, the low pressure switch will
require resetting.
If any doubt exists concerning burner operation when
special equipment is involved, contact the installing
contractor or MIDCO INTERNATIONAL INC. (front cover).