Bosch C920ES Service Bulletin

Service Bulletin G3-33
Models: 715ES, C800ES, C920ES, C920ESC, 2400ES, 2700ES, Evolution 500, Integra 500
EA Error Code Troubleshooting
WARNING: This bulletin includes troubleshooting that
should ONLY be performed by a qualified professional.
Introduction
EA Error code explanation:
The unit could not establish a burner fl ame signal at start up.
Typically, the unit will make several attempts to establish a fl ame
before it locks out on an EA error code.
Tools needed:
Phillips head screwdriver

Manometer

Digital Multi-meter

Preparation
Remove cover from heater (see Section 2.2 in Installation Manual).
Troubleshooting
1. Check for spark and fl ame through heat exchanger site window
(Figure 1, pos. 1) with water fl owing. Ignition electodes are
located on inner left side of site window. Record observations
(e.g. Does heater spark several times and lock out? Does it
immediately go to the error code?).
2. Check for correct gas type on label on right side of heater
cover. The heater's gas type can also be confi rmed using the
control board diagnostics feature (see installation manual). If
gas type is incorrect, heater will not operate correctly.
3. Make sure the unit plugged into a clean power supply (e.g.
dedicated socket on a dedicated breaker with no extension
cords, or surge protectors).
C 920 ES/ESC shown - heater design may
vary slightly depending on model
4. Check ground quality on electrical receptacle where appliance
is plugged in.
5. Is the unit installed above 2000 ft elevation? If so, was the unit
calibrated for the elevation? If not, follow the instructions in the
manual for installations at higher elevations.
6. Make sure there are no blockages in the combustion air or
exhaust vent piping. If the unit is drawing combustion air from
inside the building, make sure it has 50 cubic feet per 1000
BTU per hour available. For example, a 175 kBTU heater
requires 8750 cubic feet of air (175000 BTU / 50 ft³ = 8750 ft³).
Figure 1