Form I-UDA, P/N 195673 Rev 13, Page 13
FIGURE 9 - Gas
connection is at
the pipe nipple that
extends outside the
cabinet.
Illustration shows
both a vertical and
horizontal gas supply;
requirements are the
same.
6.1. Valve Outlet
or
Orifice Pressure
Setting
Measuring valve outlet gas pressure cannot be done until the heater is in operation. It
is included in the steps of the “Check-Test-Start” procedure in Paragraph 24. The fol
-
lowing warnings and instructions apply.
WARNING: Valve outlet gas pressure must never exceed 3.5”
w.c. for natural gas and 10” w.c. for propane gas.
For Natural Gas:
When the heater leaves the factory, the combination gas valve is set
so that the valve outlet gas pressure for a single-stage valve or high fire of a two-stage
valve is regulated to 3.5” w.c. Low fire on a two-stage valve is set to 1.8” w.c. Inlet sup
-
ply pressure to the valve for natural gas must be a minimum of 5” w.c. or as noted on
the rating plate and a maximum of 14” w.c.
For Propane Gas:
When the heater leaves the factory, the combination gas valve is
set so that the valve outlet gas pressure for a single-stage valve or high fire of a two-
stage valve is regulated to 10” w.c. Low fire on a two-stage valve is set to 5.0” w.c.
Inlet supply pressure to the valve for propane gas must be a minimum of 11” w.c. and
a maximum of 14” w.c.
Before attempting to measure or adjust valve outlet gas pressure, the inlet supply
pressure
must
be within the specified range both when the heater is in operation and
on standby. Incorrect inlet pressure could cause excessive valve outlet gas pressure
immediately or at some future time. If natural gas supply pressure is too high, install a
regulator in the supply line before it reaches the heater. If natural gas supply pressure
is too low, contact your gas supplier.
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Instructions
1)
Locate the 1/8” output pressure tap on the valve (See
FIGURE 10
). With the man
-
ual valve turned off to prevent flow to the gas valve, connect a manometer to the
1/8” pipe outlet pressure tap in the valve. NOTE: A manometer (fluid-filled gauge)
is recommended rather than a spring type gauge due to the difficulty of maintain
-
ing calibration of a spring type gauge.
Check Valve Outlet
Pressure (can only be
done after heater is
operating)
NOTE:
If operating at
high altitude, outlet
pressure requires
adjustment. Follow
instructions on page 14.
NOTE: Gas Conversion
Kits are available
for changing from
propane gas to natural
gas or natural gas to
propane gas. A factory-
authorized conversion
kit MUST be used.
FIGURE 10 - Top View
of Valves showing
Outlet Pressure Tap and
Adjustment Locations
Single-Stage
Valve
1/8” Output
Pressure Tap
1/8” Output
Pressure Tap
Inlet
Pressure
Tap
Two -Stage Valve
Output
Adjustment
Screw
Adjust High
Pressure Output
Adjust Low
Pressure Output
Inlet
Pressure
Tap