Bosch_Eubleshooting Bosch EA Error Code Troubleshooting

User Manual: Bosch EA error code troubleshooting

Open the PDF directly: View PDF .
Page Count: 2

Model: 250SX, 250SXO, 635ES, 635ESO, 2400E, 2400EO

EA Error Code Troubleshooting

Service Bulletin: TWH-G2-09

Introduction

Follow the procedures below and report results to Bosch

Technical Support. This will assist in determining the cause and

solution to the problem.

EA Error code explanation:

Burner flame not recognized by control unit with water flow.

Tools needed:

u Voltmeter/ multimeter

u Phillips head screwdriver

Procedure

Remove cover from heater (see Section 2.2 in Installation Manual).

Check for spark and flame through window in heat exchanger with

water flowing (0.8 gpm flow rate required) (Figure 1).

Viewing

window

Figure 1

Viewing

w

in

dow

A. If there is no spark with water flow and an EA error occurs:

1. Check connection of 2 yellow wires (with braided covering)

to bottom of electrodes (Figure 2). The inner metal wire con-

nector must be clean and tight on electrodes. It is possible

for the gray insulating sleeve to slide up, preventing good

electrical connection. If the connector is corroded, try clean-

ing contacts, otherwise replace the electrode cables.

Electrode

connectors

Flame sensor

rod connector

Figure 2

de

E

lect

r

od

d

or

s

conn

ect

e

n

sor

Flame

se

e

rod con

n

n

ector

n

2. Check for correctly wired, grounded and dedicated electrical

outlet. If unsure or not correct, consult electrician.

B. If there is sparking with water flow but no flame and EA error

occurs:

1. Check for closed gas shutoff valves. Gas must be supplied to

heater.

2. Check for correct gas type on label on right side of heater

cover. If incorrect, heater will not operate correctly. The

heater’s gas type can also be verified using the control unit’s

diagnostic feature. See bulletin TWH-G2-07 Control unit

diagnostics. It is possible to convert the heater gas type us-

ing a combustion gas analyzer (to recalibrate the CO2) and

a conversion kit (part number 8 719 002 176).

3. Check for air in the gas line: On new installation or after work

has been performed on gas line: Reset error and start water

flowing to cycle the heater and purge air from the gas line.

Error may have to be reset several times to eliminate all the

air.

http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

1 2 | TWH-G2-09 | 250SX, 250SXO, 635ES, 635ESO, 2400E, 2400EO Service bulletin

Data subject to change without notice | Printed in the USA | BTC 711002302 A | 12.2008 Bosch Thermotechnology Corp.

Bosch Thermotechnology Corp.

50 Wentworth Avenue

Londonderry, NH 03053

Tel: 1-866-642-3198

Fax: 1-603-584-1681

www.boschpro.com

4. Check for signs of moisture inside heater:

a. Turn off water flow, reset error, turn off heater power and

unplug power cord.

b. Turn off gas supply to heater.

c. Remove heater cover, metal holding bracket and black

plastic air intake duct (with metal attenuator if present)

(Figure 4). Do not lose large O-ring.

d. Look inside the white plastic tube in front of the fan for

signs of dust, powder or moisture.

e. Examine electrode gasket (between top of electrode plate

and bottom of burner) for signs of moisture, discoloration

or staining. See figure 3.

Electrodes

Flame

sensor rod

Gasket

Figure 3

El

ect

r

odes

F

l

ame

se

n

so

r r

od

Gasket

Gasket

f. Remove 3 screws from flat metal plate on top of gas valve

(Figure 3). Remove plate and check for signs of moisture,

rust or corrosion.

Holding

bracket

screws

Air intake

duct

Air intake

duct screws

Figure 4

Ho

ld

in

g

b

r

ac

k

et

s

crew

s

A

ir in

ta

k

e

d

uct

A

ir inta

k

e

duct

sc

r

e

w

s

Flat metal

plate

Signs of dust, powder or discoloration may indicate

condensate damage. Moisture, rust or puddles of water

may indicate rain damage. Once moisture gets into gas

valve, it will no longer operate safely and must be replaced

by a qualified technician using a combustion gas analyzer.

Refer to Bulletin G2-28 and G3-12.

Moisture can get into gas valve and not be visible.

Discoloration of electrode gasket indicates damage to

electrodes. Refer to Bulletin G2-23 to clean or replace

electrodes. If moisture is found, see Bulletin G2-08

for condensation and rain prevention requirements.

5. Check for blocked exhaust or intake venting.

6. Check for loose wire connection from front of gas valve.

7. Check for broken yellow paint on fuel/air mixture adjustment

screws. If either adjustment has been changed, the fuel/air

mixture could be incorrect. Adjustment can only be made with

the use of a combustion gas analyzer. See Bulletin G2-12 for

adjusting CO2.

8. Check voltages at gas valve: Remove electrical connection

from front of gas valve, reset error and measure voltage be-

tween left two wires and right two wires with water flowing.

The readings should be about 24VDC. If not, call Bosch Tech

Support for further information.

C. If there is sparking with water flow and flame but EA error still

occurs:

1. Check for tight wire connections on the flame sensor rod

and the electrodes. Make sure all connections are free of

corrossion. (Figure 3).

2. Clean flame sensor rod. See Bulletin G3-23.

Call Bosch Water Heating with troubleshooting results, exact gas

pressure readings or further questions. If a gas technician is at

the heater, the technician should call from heater with Unit

number (our record referring to consumer’s location and heater

details). If no Unit record has been started, we will need

consumer’s name, address, phone number, heater model name

and number, serial number, date of installation and installation

details.