Measuring Gas Pressure - Bosch GWH C 920 ES Instruction Manual

3.13 Measuring gas pressure

Gas pressure must be measured upon installation.
Connecting manometer
B Shut off gas supply at installer supplied shutoff valve
for this water heater.
B Remove front cover and locate inlet gas pressure test
port (see Fig. 36).
B Loosen screw inside left test point fitting (do not
remove) and connect manometer tube to test point.
Static Pressure Test
B Turn gas supply back on.
B Record static gas pressure reading in table 15.
Operating Pressure Test
B Press ON/OFF button
B Press and hold "Program"
ON/OFF button
Fig. 35
B As soon as '188' is displayed, release "Program"
button , and the display reads P2.
B Press or until P1 appears.
Note: While in this mode the appliance will run
constantly at maximum
maximum water flow.
Gas type
minimum pressure
Table 14
Minimum inlet gas pressure under full operation
B Operate all other gas appliances (except heater) on
same gas piping system at maximum output.
B Turn on high volume of hot water flow (at least 6
gpm) and burner will light. If heater display reverts to
P2, open more hot water fixtures to allow sufficient
flow. Press until P1 reappears on the display.
B Record lowest operating gas pressure reading in
table 15.
Gas pressures lower than 3.5" W.C. for Natural Gas or
8" W.C. for LPG will result in insufficient degree rise to
the hot water being used, reduced hot water volume,
6 720 608 836
to turn off the appliance.
button and press
to turn appliance ON.
power and allow
NG LPG
3.5" WC 8" WC
possible error code faults and must be corrected. See
Gas Connections, chapter 3.8, page 22.
P1 fan speed:
Factory default: NG: 52, LP: 53
Lowering P1 fan speed reduces the maximum BTU
input.
As a temporary measure if the gas pressure in P1 is
below specification, lower P1 fan speed incrementally
until minimum inlet gas pressure reaches specified
range (table 14). After raising gas pressure, reset
appliance to P1 factory default setting (NG: 52, LP: 53).
Fig. 36 Gas pressure test port (left tapping)
Static Gas Pressure Reading (see Chapter 3.13)
enter here: ___________________ Date: ___________
Operating Gas Pressure Reading (see Chapter 3.13)
enter here: ___________________ Date: ___________
Table 15
Installation instructions
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