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Problem Possible Cause Test/Action
Popping noise at burner
assembly during simmer mode
Burner assembly damaged or dirty with food
debris
Replace or clean the burner assembly.
Burner assembly cracked or warped Replace the burner assembly.
Supply gas impurities
Especially common with LP gas. If possible, try a
different gas supply.
Flame appearance on burner
assembly or assemblies
▪ Tall flame
▪ Yellow flame
▪ Pulsing flames
Port holes in burner assembly not to specification,
damaged, or dirty
Replace or clean the burner assembly.
Incorrect gas orifices Check the stamp number on the orifices.
Gas pressure Check the gas pressure with a manometer.
Secondary gas regulator within 10 ft of unit
regulator
The secondary regulator and unit regulator should
be at least 10 ft apart.
Unit regulator damaged Check the gas pressure with a manometer.
No knob or lighted knob display No light in light module
▪ Check for 120 VAC to the DC rectifier.
▪ Check for 16 VDC from the DC rectifier.
▪ Check the light module for continuity.
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.
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.
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
be within PLUS .5” wc and MINUS 0.0” wc of the
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.
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” wc - 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.
CG Contemporary Gas Cooktop Service Manual
Troubleshooting Guide
service.subzero.com
828389 REV. A 06/2018
31
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