Gas Pressure Testing - Wolf CG Series Service Manual

Problem
No knob or lighted knob display
REMOVE THE GAS VALVE BYPASS SCREW ORIFICE
Each gas valve has two bypass screw orifices installed on the
valve body. On sealed burners, this bypass screw is not
adjustable. If there is concern that the wrong bypass screw has
been installed into a gas valve, the size of the bypass screw can
be confirmed by comparing the number stamped on the bypass
screw to the orifice chart .

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. Also, because there are three different
sizes of burner assemblies on each unit, pressure issues can
affect different sized 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" - 5.5" 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" - 10.5" 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.
824779 REV. C
CG Series Gas Cooktops Service Manual
Possible Cause
No display lights
No light in bezel
Test/Action
check voltage to display light board.
1 Check voltage to bezel.
2 Check the electrical connection.
3 Replace the bezel.
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 9.2 K 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 9.2 K burners in the simmer
range, while connected to the other 9.2 K 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" - 5.5"
WC.
Example:
Low flow manifold pressure reading taken with
right front burner on low simmer on CG304P/S-LP with liquid
propane (LP) was 9.7" WC. Low flow pressure is bad. Outside
of range of 10" - 10.5" WC.
Maximum Flow Pressure
Maximum flow pressure is the manifold pressure when all
burners are set to High. It is normal for the pressure to drop
slightly. The difference in pressure from the low flow pressure to
the maximum flow pressure must be less than .5" WC.
Example:
Low flow manifold pressure is 5.4" WC on
CG365T/S. Maximum flow manifold pressure is 5.2" WC.
Pressure test is good. Pressure drop was .2" WC, and low flow
was 5.4" WC. Unit is not experiencing a gas pressure issue.
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MINUS
0.0" WC of the