Gas Pressure Testing - Wolf CG Series Service Manual

Troubleshooting Guide
Problem
Popping noise at burner
assembly during simmer mode
Flame appearance on burner
assembly or assemblies
▪ Tall flame
▪ Yellow flame
Pulsing flames
▪
No knob or lighted knob display

GAS PRESSURE TESTING

Testing gas supply pressure to a unit is a critical tool in properly
diagnosing a problem. Gas supply pressure issues are
common, and many times they are the root cause of recurring
issues. On CG units, each burner has an individual spark
module. There are no fuel-to-air ratio adjustments. Intermittent
sparking issues, flame quality issues, and ignition issues that
affect all burners are almost always related to gas pressure or
the supply regulator. Because there are also three different sizes
of burner assemblies on each unit, pressure issues can affect
different sizes of burners in different ways. Gas pressure must
be checked by the method listed. The reason for this is so that
recorded pressures can be used to diagnose a specific issue.
Natural Gas Specifications
The supply pressure to the inlet of the unit regulator must be
between a minimum of 7" water column (wc) and a maximum of
14" wc.
The outlet of the regulator must be 5" +.5" wc/-0.0" wc.
The maximum pressure drop from maximum flow to low flow
must be less than .5" wc.
Liquid Propane Specifications
The supply pressure to the inlet of the unit regulator must be
between a minimum of 11" wc and a maximum of 14" wc. The
outlet of the regulator must be 10" +.5" wc/-0.0" wc.
The maximum pressure drop from maximum flow to low flow
must be less than .5" wc.
Connecting to the Unit Manifold
To check pressure on a CG unit:
1 Uninstall the unit.
2 Remove the burner pan.
3 Once the burner pan is removed, reassemble the burners.
828386 REV. A 06/2018
CG Professional Gas Cooktop Service Manual
Possible Cause
Burner assembly damaged or dirty with food
debris
Burner assembly cracked or warped
Supply gas impurities
Port holes in burner assembly not to specification,
damaged, or dirty
Incorrect gas orifices
Gas pressure
Secondary gas regulator within 10 ft of unit
regulator
Unit regulator damaged
No light in bezel
No power to the unit
Test/Action
Replace or clean the burner assembly.
Replace the burner assembly.
Especially common with LP gas. If possible, try a
different gas supply.
Replace or clean the burner assembly.
Check the stamp number on the orifices.
Check the gas pressure with a manometer.
The secondary regulator and unit regulator should
be at least 10 ft apart.
Check the gas pressure with a manometer.
1 Check the voltage to the bezel.
2 Check the electrical connection.
3 Replace the bezel.
Check/connect power to the unit.
WARNING
Do not over-tighten the burner assembly
screws. The burner is designed to have the
burner pan between the burner assembly and
the orifice holder. A small amount of gas
leakage is normal during testing.
4 Disconnect the main gas tube from a 9.2K orifice holder,
and connect the manometer to the main gas tube. Set the
burner to High.
WARNING
Professional models have bezel connectors
that may short to the knob. Connect the
bezel, and install it loosely in the display
bracket.
Static Pressure
Static pressure is the gas pressure when there is no gas
movement. Taking this pressure is not an effective diagnostic
tool. Pressure will equalize across any regulator in the gas
supply system. It is not possible to determine what pressure
should be recorded when checking any part of unit by static
pressure.
Low Flow Pressure
Low flow pressure is manifold pressure on the unit taken when
there is minimum gas flow. This pressure will provide an idea if
the unit regulator is operating properly. Low flow pressure must
PLUS
be within .5" wc and
designated manifold pressure. Low flow pressure on CG units is
obtained by lighting one of the 9.2K burners in the simmer
range, while connected to the other 9.2K burner main gas line.
Example:
Low flow manifold pressure reading taken with left
rear burner on low simmer on CG365T/S with natural gas was
5.4" wc. Low flow pressure is good. It falls in range of 5" wc -
5.5" wc.
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service.subzero.com
MINUS
0.0" wc of the