Measuring Gas Pressure - Bosch 940 ESO Manual

Fig. 30 Space heating diagram
[1] Hot water outlet
[2] Cold water inlet
[3] Pressure relief valve
[4] Gas supply
[5] Shut off gas valve
[6] Thermal expansion tank (as required)
[7] Atmospheric vacuum breaker
[8] Cold inlet
[9] Check valve
[10] Pump
[11] Thermostatic mixing valve
[12] Thermometer (optional)
[13] DHW outlet
[14] Water to water heat exchanger
[17] Thermostat
[18] Space heating zone
[19] Zone controller
[20] Space heating pump
[21] Expansion tank
[22] Pressure relief valve
8.6

Measuring gas pressure

Confirm gas pressure upon installation.
Connecting manometer
▶ Shut off gas supply at installer supplied shutoff valve for this water
heater.
▶ Remove front cover and locate inlet gas pressure test port (see
Fig.32).
▶ Loosen screw inside left test point fitting (do not remove) and
connect manometer tube to test point.
Static Pressure Test
▶ Turn gas supply back on.
▶ Record static gas pressure reading in table 13.
940 ESO
Operating Pressure Test
▶ Press ON/OFF button into ON.
▶ Press and hold simultaneously buttons
seconds, until display reads P2.
Fig. 31
▶ Press to enter P2 adjustment. The current setting will appear on
P
the display (factory default).
+
▶ Press or until P1 appears.
Note: While in this mode the appliance will run constantly at maximum
power and allow maximum water flow.
For inlet gas pressure adjustment consider the following table:
Gas type
p 3.5" WC
in
Table 12 Minimum inlet gas pressure under full operation
▶ Operate all other gas appliances (except heater) on same gas piping
system at maximum output.
▶ 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
▶ Record lowest operating gas pressure reading in table 13.
Installation instructions | 23
+
, and for 3
P
NG LPG
8" WC
+
until P1 reappears on the display.
6 720 644 956 (2016/05)