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A minimum of 7" WC and a maximum of 10.5" WC upstream pressure under load, and no load conditions must
be provided for natural gas or a minimum of 11" WC and a maximum of 13" for propane.
GAS PRESSURE REGULATOR
The gas pressure regulator located in the gas valve is preset nominally at 4" WC for natural gas, and 11" WC
for propane. Between the gas valve and the burners is a 1/8" pipe plug. The pressure at this point, taken with
a manometer, should be about 3.7" WC natural gas and 10.5" WC propane. Models 181, 261, 331, and 401
should be 3.9 wc natural gas. If an adjustment is needed, turn adjustment screw clockwise to increase pressure,
or counter-clockwise to decrease pressure.
VENTING OF DIAPHRAGM GAS COMPONENTS
Gas train components that have diaphragms in their construction are supplied with a bleed line connection
that must be connected to the outside atmosphere as required by the National Fuel Gas Code. Under NO
circumstances shall bleed lines terminate in the gas utilization equipment flue or exhaust system.
Fig # 8185.2
* Models 181, 261, 331, and 401 are Low NOx units and are not available in propane.