Gas Burners - Vulcan-Hart VL Series Service Manual

VL BOILER BASE SERIES CONVECTION STEAMERS - SERVICE PROCEDURES AND ADJUSTMENTS
D. With the thermocouple disconnected,
connect the meter leads to the tube and
threaded end. Turn the power switch ON
and light the pilot. Hold down the OFF/
PILOT/ON knob and allow the pilot to heat
the thermocouple for one to two minutes.
Take an open circuit reading and compare
with the chart below.
1) 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) in then check for proper
operation.
3. If after checking and/or 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.
NOTE: Gas combination control valves are not
serviceable and should not be disassembled. Once
you have isolated the problem to this control, replace
it. Do not attempt to repair the assembly.
THERMOCOUPLE DC MILLIVOLT READINGS
CLOSED
CIRCUIT
(CONNECTED)
Typical 15
Range 10-20

GAS BURNERS

CERTAIN PROCEDURES IN THIS
SECTION REQUIRES ELECTRICAL
TEST OR MEASUREMENTS WHILE
POWER IS APPLIED TO THE
MACHINE. EXERCISE EXTREME
CAUTION AT ALL TIMES. IF TEST
POINTS ARE NOT EASILY
ACCESSIBLE, DISCONNECT
POWER, ATTACH TEST
EQUIPMENT AND REAPPLY
POWER TO TEST.
The main gas burners are located under the boiler for
heating and number five to seven depending on the
steamer model. They are made of aluminized steel
F24650 Rev. A (1017)
OPEN CIRCUIT
(DISCONNECTED)
20-35
Page 34 of 93
with lanced type ports and have adjustable air shutters
in the front. Fixed orifice type hoods extend from the
manifold to establish gas flow to each burner.
Air Shutter Adjustment
1. Ignite the burners and allow to heat up for at least
five minutes.
2. Verify the manifold pressure as outlined under
GAS MANIFOLD PRESSURE ADJUSTMENT.
3. Loosen the set screw on the burner being
adjusted. Closing the air shutter will decrease
primary air to the burner and opening the shutter
will increase primary air the burner.
4. Monitor the burner flame and set the air shutter
opening as follows:
A. Open up the air shutter until the inner portion
(blue) of the flame lifts off the burner port
and then turn the air shutter back until the
flame touches the burner port again. A slight
tinge of orange and yellow in the flame is
acceptable. An extremely yellow flame
indicates too little primary air (oxygen),
producing poor burning characteristics and
the heating efficiency drops off. A byproduct
of this would be soot (carbon).
Factory air shutter settings are: natural gas
- open approximately ½ inch; propane gas -
fully open.
5. After the air shutter adjustment is made, tighten
the set screw.
Inspection
Remove gas burners by lifting burner up and sliding it
to the rear just enough to clear the gas orifice hood.
Lower the front end of burner and bring it forward
under the gas manifold pipe. Inspect burner for
clogged or damaged ports. Clean or replace as
necessary. When reinstalling burners, ensure that
locating pin is in the hole for proper positioning and to
prevent burner from rolling over.