Program Button; Locked Condition; Maintenance And Service; Annual Maintenance - Bosch 520PN Applications Manual

After following instructions indicated in "Troubleshooting" section,
▶ press reset button firmly in order to return heater to normal
operation.
Fig. 61 Reset button
If the problem persists, contact your installer.
6.8

Program button

Fig. 62 "Program" key
6.8.1 Memorizing selected temperature
+
▶ Press buttons or to select desired temperature.
▶ Hold "Program" button for 3 seconds to save temperature.
When LCD stops blinking, temperature is saved in memory.
Using "Program" function
In order to select memorized temperature
▶ Press "Program" key.
LCD shows pre-memorized temperature, which is now the hot water
selected temperature.
6.9

Locked condition

This condition is only valid for appliances with one or more remote
controls installed.
Fig. 63 Locked condition
Whenever LCD shows , the temperature setting cannot be
adjusted because the appliance is in use by a user which already
selected a different temperature. Appliance will be automatically unlock
5 minutes after closing hot water tap.
C 1210 ES/ESC
7

Maintenance and service

WARNING:
▶ Always shut off the electrical power supply, shut off
the manual gas valve and shut off the water valves
whenever servicing.
NOTICE:
▶ Check and clean the complete water heating system
once a year.
▶ Carry out a maintenance overhaul if necessary.
Immediately repair defects to avoid damage to the
system.
Annual maintenance table
1. Inspect venting system
2. Inspect combustion chamber
3. Inspect burner
4. Inspect condensate trap
5. Inspect water filter
Table 32 Annual maintenance
7.1

Annual maintenance

(To remove front cover, see page 8.)
Venting System
• Venting system - inspect inside of flue pipe for any blockage or
restriction. Observe burner flames during heater operation. (front
cover 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.76, #14) 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
Section4.4, page 23, chapter 4.3, page 11 of this manual to verify
exhaust system and combustion air supply meets manufacturer's
specifications
Pressure Relief
• 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 on the bottom of the appliance, to the right of the cold
water inlet fitting. (See Fig.32, page 27). Close installer supplied
water shutoff and remove wireform spring clip from filter. Remove
filter, clean and or replace if damaged
Descaling
• In areas where the water supply has a high mineral content, the heat
exchanger should be 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 section7.3 for detailed
instructions on descaling the heat exchanger
Maintenance and service | 35
Every year
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6 720 644 887 (2013/02)