Measuring Gas Pressure; Electrical Connections; Electrical Power Supply - Bosch 520PN Applications Manual

4.14 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.43).
▶ 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 30.
Operating Pressure Test
▶ Press ON/OFF button into ON.
▶ Press and hold simultaneously buttons
seconds, until display reads P2.
Fig. 42
▶ 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 NG
p 3.5" WC
in
Table 29 Minimum inlet gas pressure under full operation
5

Electrical connections

5.1

Electrical power supply

For safety reasons, disconnect the power supply cord
to the heater before any service or testing is
performed.
This heater must be electrically grounded in
accordance with the most recent edition of the
National Electrical Code. NFPA 70. In Canada, all
electrical wiring to the heater must be in accordance
with local codes and the Canadian Electrical Code,
CSA C22.1 Part 1. Do not rely on the gas or water
piping to ground the metal parts of the heater.
C 1210 ES/ESC
+
or and for 3
P
LPG
8" WC
▶ 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 30.
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, possible error code faults and must be corrected. See
Gas Connections, chapter 4.8, page 24.
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 29). After upgrading gas line, reset
appliance to P1 factory default setting (NG: 52, LP: 53) or setting from
Section 4.3.7.
Fig. 43 Gas pressure test port (left tapping)
Static Gas Pressure Reading (see chapter 4.14)
enter here: ___________________ Date: ___________
Operating Gas Pressure Reading (see chapter 4.14)
enter here: ___________________ Date: ___________
Table 30
The water heater requires an electrical power supply from a 120VAC /
60Hz properly rated receptacle and must be properly grounded.
The heater is wired as shown in the wiring diagram (chapter 10, Fig.71).
Electrical connections | 31
until P1 reappears on the display.
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