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Electrical Connections; Electrical Power Supply; Position Of The Fuses In Control Unit - Bosch 940 ESO Manual

940 eso - natural gas / 940 eso - liquefied petroleum (lp) gas
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24 | Electrical connections

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 8.1, page 17.
P1 fan speed:
Factory default: NG: 54, LP: 46
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 12). After upgrading gas line, reset
appliance to P1 factory default setting (NG: 54, LP: 46) or setting from
Section 10.8.
Fig. 32 Gas pressure test port (left tapping)
Static Gas Pressure Reading (see chapter 8.6)
enter here: ___________________ Date: ___________
Operating Gas Pressure Reading (see chapter 8.6)
enter here: ___________________ Date: ___________
Table 13
Electrical connections

Electrical power supply

▶ For safety reasons, disconnect the power supply
cord to the heater before any service or testing is
▶ 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.
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 14, Fig.60).
6 720 644 956 (2016/05)
Fig. 33 Connecting power supply cord
Power cord length: 3ft.
Note: The outlet the appliance is plugged into should be clear from
possible water damage.

Position of the fuses in control unit

To check fuses, proceed as follows:
▶ Remove the front cover, see fig. 4, page 9.
▶ Remove the three screws from the control unit.
Fig. 34
▶ Remove the six screws from the back cover of the control unit, see
fig. 35, pos. 2.
▶ Check the fuses in the printed circuit board, see fig. 35, pos. 3.
Fig. 35 Fuses position
▶ After checking the fuses, reinstall all parts in reverse order.
940 ESO



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