Bosch Model GWH 425 - Manual (Page 15)

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Operation instructions
15
4.2 Lighting instructions
B STOP! Read the previous safety information.
B The gas valve must be turned off by sliding the gas
valve button to all the way to the left.
Fig. 18
B
Wait five (5) minutes to clear out any gas. If you smell
gas, STOP! Follow “B” in chapter 4.1. If you don’t
smell gas, go to next step.
B The pilot burner window is located in the front center
of the cover.
B Slide the gas valve button to the position .
Fig. 19
B
Fully depress gas valve button.
Fig. 20
B With the gas valve button fully depressed, light pilot
by pushing the piezo button. This step may have to
be repeated.
Fig. 21
B
Observe the pilot flame through the peephole. The
gas valve button should be held down for at least 15
seconds with pilot burning before releasing. When
the gas valve button is released, the pilot should
continue to burn.
- If the gas valve button does not pop out when
released, stop and immediately call your service
technician or gas supplier.
- If pilot does not stay lit, repeat all steps.
- If pilot will not stay lit after several tries, slide the gas
valve button all the way to the left and call service
technician or gas supplier.
B The heater will now fire at minimum power when
water is drawn at a rate greater than the required
activation flow rate.
Note: If main burner should fail to ignite, make sure pilot
is burning. If not, repeat lighting steps.
Note: The GWH 425 PN operates in two modes. See
SETTING THE WATER TEMPERATURE.
4.3 To turn off appliance
B Slide the gas valve button all the way to the left and
turn off the installer supplied manual gas shutoff on
the supply line to the heater.
Fig. 22