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Maintenance and service
6 Maintenance and service
The unit should be checked once a year by a gas
technician. If repairs are needed, the repairs should be
done by a gas technician.
6.1 Annual maintenance
(To remove front cover, see page 6.)
Venting System
• Venting system - inspect inside of flue pipe for any
blockage or restriction. Observe burner flames
during heater operation. (Vent pipe must be
removed). Inspect the combustion air inlet pipe for
blockage or debris. Inspect combustion air and
exhaust terminations for blockage or debris.
Combustion chamber
• Inspect burner observation window (Fig. 64, #10) for
cracks or spillage of flue gases. Observe burner
flames during heater operation. Flames should be
steady and blue with no signs of yellowing. Yellow
burner flames are an indication of improper
combustion. Refer to Section 3.4 & 3.3 of this
manual to ensure that exhaust system and
combustion air supply meets manufacturer's
specifications.
Pressure relief valve
• Manually open the pressure relief valve to ensure
proper operation.
Inlet water filter
• Verify the inlet filter screen is clean and undamaged.
The inlet water filter is located inside the cold water
inlet fitting on the right side of the appliance (See
Fig. 53, page 32). Close installer supplied cold water
shutoff and loosen slotted screw on inlet fitting.
Water will drain from the appliance. Remove
cylindrical filter inside.
Fig. 53 Water filter
1 Inlet water filter
2 Water filter
Descaling
• In areas where the water supply has a high mineral
content (see Table 13, page 25), the heat exchanger
should be periodically flushed with a descaling
solution. Scale build up will shorten the life of the
water heater and damage resulting from scale is not
covered under warranty. Refer to section 6.3 for
detailed instructions on descaling the heat
exchanger.
Heat exchanger fin coils
• Inspect heat exchanger fincoil for soot build-up or
blockage. To access fincoil, venting must be
removed from flue gas exhaust accessory. With
venting removed and inspect fincoil below with a
flashlight. If there is evidence of soot build-up or
blockage, the heat exchanger should be removed by
a professsional and cleaned thoroughly. To remove
the heat exchanger, consult service bulletin at
www.boschhotwater.com.
6.2 Winterizing for seasonal use
Installation instructions state that the water heater must
not be installed in a location where it may be exposed to
freezing temperatures. If the heater must be left in a
Warning: Always turn off the electrical
power supply, turn off the manual gas
shut off valve and turn off the water shut
off valves whenever servicing.
Caution:
B Check and clean the complete water
heating system once a year.
B Carry out a maintenance overhaul if
necessary. Immediately repair defects to
avoid damage to the system.
Annual maintenance table
Every year
1. Inspect venting system X
2. Inspect combustion chamber X
3. Inspect burner X
4. Inspect condensate trap X
5. Inspect water filter X
Table 16 Annual maintenance