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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.
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.
Example:
Low flow pressure is 10" wc on CG304P/S-LP
after the gas company raised the supply pressure. Maximum
flow pressure is 9.5" wc. Pressure drop is .5" wc. Unit fails
pressure test.
Common Reasons for Pressure Issues
Most often, an excessive drop in pressure between low flow
and maximum flow is caused by insufficient volume of gas.
Ensure the following items are to specification:
▪
If a flex-line is installed, it must be at least
1
/
2
" internal
diameter (ID) and no longer than 3 feet long. Many times,
the line is
1
/
2
" OD.
▪
Shut-off valve should be
3
/
4
". Most of the
1
/
2
" shut-off ball
valves are
3
/
8
" through the ball.
▪
Ensure the supply pressure stays at or above the minimum
supply pressure at full load. Full load is when all gas
appliances in the home are on including the cooktop.
▪
Supply line to the unit is not
3
/
4
".
Note: If the customer has multiple issues, correct the flex-line
and shut-off first before requesting that the customer replace
the gas line.
CG Professional Gas Cooktop Service Manual
Troubleshooting Guide
GAS PRESSURE TESTING (continued)
service.subzero.com
828386 REV. A 06/2018
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