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VL BOILER BASE SERIES CONVECTION STEAMERS - SERVICE PROCEDURES AND ADJUSTMENTS
NOTE: If adjustments in gas or pilot pressure settings
are made, always replace the adjustment cover screw
to ensure proper gas control operation.
Fig. 13
If the adjustment does not result in a pilot flame of
proper size, then gas might not be flowing properly to
the pilot. Check for a plugged pilot orifice, a kinked or
plugged pilot gas supply tube and for low gas supply
pressure. The pilot operates unregulated at gas
supply pressures while the pressure regulator in the
combination control valve regulates pressure to the
main burners only. Visually check the thermocouple
tip (hot end) and tube lead for kinks or pinches that
might be causing a short between the tube and the
wire inside. Also, check the threaded connector tip for
corrosion, tarnish or dirt which can cause a poor
connection. If the thermocouple shows either of these
signs, it should be replaced with a new one.
NOTE: The connection of the tubing from the
thermocouple tip to the control valve is an electrical
connection and must be clean. Do not use any sealing
compound on the threads or overtighten the threaded
connection. Finger tighten the nut plus 1/4 turn with a
wrench. Overtightening the nut could crush the
insulator, shorting the thermocouple.
If the pilot flame is correct and there are no drafts, then
the problem is in the thermocouple output voltage or
the gas solenoid valve in the combination control.
Check the thermocouple output voltage as follows:
1.
Turn the power switch OFF and disconnect the
thermocouple from the gas combination control
valve.
2.
Check the thermocouple DC millivolt output with
a VOM. If a meter is not available, replace the
thermocouple with a new one and check
operation again.
A.
Install a thermocouple adaptor into the
connection on the gas combination control
valve. Screw the thermocouple in to the
adaptor then connect the meter leads to it.
See TOOLS under for information on
thermocouple adaptor. If a thermocouple
adaptor is not available then turn the power
switch OFF, disconnect the thermocouple
from the gas combination control valve and
proceed to step 2D.
B.
Turn the power switch ON and light the pilot.
Allow the pilot to heat the thermocouple for
one to two minutes and take a closed circuit
reading. Compare the readings with the
chart below.
1)
2)
3)
C.
Turn the power switch OFF and disconnect
the thermocouple adaptor from the gas
combination control valve and
thermocouple.
Page 33 of 93
If the reading is less than the minimum
or thermocouple is not operating as
described, replace the thermocouple
as outlined under PILOT AND
THERMOCOUPLE ASSEMBLY (GAS
MODELS) then check for proper
operation.
If the reading is within the range listed
in the chart below then thermocouple is
operating properly. Reconnect the
thermocouple to the gas combination
control valve.
If after replacing thermocouple, the
pilot or main burners are still not
functioning properly, then a problem in
the gas combination control valve
exists as well. Replace the
combination control valve as outlined
under GAS COMBINATION
CONTROL VALVE then check for
proper operation.
F24650 Rev. A (1017)
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