Bosch Appliances 2400E NG, 2400E LP manual Maintenance and service, Annual maintenance

5Maintenance and service

Warning: Always turn off the electrical power supply, turn off the manual gas valve and turn off the manual water control valves when servicing heater.

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

5.1Annual maintenance

(To remove front cover, see page 5.)

Venting System

•Venting system - inspect inside of flue pipe for any blockage or restriction. Observe burner flames during heater operation. Verify that the damper inside flue gas exhaust accessory is able to move freely. (Vent pipe must be removed in order to access damper). 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. 46, #10) for cracks or leakage 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 3.5 & 3.6 of this manual to verify 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 within the ¾" cold water inlet on the bottom right side of the appliance (See Fig. 38). Close installer supplied cold water shutoff and remove cold water supply pipe. Remove filter, clean or replace if damaged.

INLET

FILTER

Fig. 38

Descaling

•In areas where the water supply has a high mineral content, the heat exchanger may need to 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 section 5.3 for detailed instructions on descaling the heat exchanger.

Heat exchanger

•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, manually hold open damper 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 TWH-G2-22 at www.boschhotwater.com.

5.2Winterizing for seasonal use

Please note that 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 space which is likely to experience freezing temperatures (less than 36° F), all water must be drained from the heater. If precautions are not taken, resulting damage will not be covered under the warranty. NOTE: Use of agents such as anti-freeze is not recommended as they may cause damage to the water heater's internal components.

1.Turn on/off switch on the water heater to the off (O) position and unplug power supply cord. The display should be blank.

2.Shut off gas supply to heater.

3.Shut off the water supply to the water heater using installer supplied shutoff valve.

4.Open hot water taps to drain and relieve pressure from the plumbing system. If water continues to flow after 5 minutes, a plumbing crossover is present and must be corrected before proceeding.

5.Disconnect inlet and outlet water pipes from the water heater. Place a small bucket underneath the water heater to catch residual water remaining inside the water heater. Save washers for future use.

6.Using an air compressor, blow short bursts of air (100 PSI Maximum) through the inlet water connec- tion until there is no water coming out of the outlet water connection of the heater.

7.Reconnect water fittings and return heater to service when danger of freezing has passed.