Bosch Appliances 250SX LP, 250SX NG manual Troubleshooting Display Cause Solution, Chapter

Page 26

Troubleshooting

Display

Cause

Solution

 

 

 

E9

Temperature limiter opened circuit (overheat).

Check connections.*

 

Trips at 220F (104C).

Check heat exchanger condition.*

 

 

 

EA

No ionization during safety time (safety time out).

Check gas pressure.*

 

Note: appliance makes 3 ignition attempts

Check that gas is not diluted with air, as a result

 

before entering error mode “EA”.

from recent gas pipeline rework.*.

 

 

Check if vent terminal is blocked (especially when

 

 

the appliance starts up for some seconds and then

EC

The ionization signal momentarily disappeared

looses ionization signal).*

 

more then 5 times in less then 30 seconds.

Check ionization electrode.*

 

 

Check for a proper ground.*

 

 

 

FA

Leakage error (gas valves do not close gas

Check gas valve and control unit.*

 

circuit).

 

 

 

 

F7

Ionization error (flame sensing at stand-by).

Check control unit.*

 

 

 

E0

Internal software/hardware failure.

Check control unit.*

 

 

 

A7

Hot water temperature sensor/receiver defect

Check water temperature sensor/receiver and

 

(from control unit).

connections.*

 

 

Check room area temperature where heater is

 

 

located, it must be above 36°F (2°C)

 

 

 

A9

Hot water temperature sensor/receiver mis-

Close water tap and allow 30 seconds for purging

 

assembled (from control unit).

time.

 

Note: if display shows “A9” flashing, the

Open water tap and wait for 2 minutes to see if A9

 

appliance can be operated normally, but

message is deleted from the display.

 

performance may be affected.

Check that the water temperature sensor/receiver is

 

 

properly assembled in the water pipe.*

 

 

Check that the water temperature sensor/receiver is

 

 

in proper condition.*

 

 

 

C1

FAN rotation too low at start-up (from control

Check supply voltage.*

 

unit).

Check fan and connections.*

 

 

Check control unit.*

 

 

Check if vent terminal is blocked or if vent terminal is

 

 

according with chapter 2.9. *

 

 

Check CO2 levels (see chapter 9).*

 

 

 

C6

FAN rotation too low at operation (from control

Check supply voltage.*

 

unit).

Check fan and connections.*

 

 

Check control unit.*

 

 

Check if vent terminal is according with

 

 

chapter 2.9.*

 

 

 

C7

No rotational speed sensor signal from FAN

Check fan and connections.*

 

 

Check control unit.*

 

 

Check CO2 levels (see chapter 9).*

CA

Water flow signal over specified maximum value

Check water valve and flow sensor.*

 

 

 

E2

Inlet temperature sensor fault

Check water temperature sensor/receiver and

 

 

connections.*

 

 

Check room area temperature where heater is

 

 

located, it must be above 36°F (2°C)

 

 

 

A2

Overheat protection fault

Check connections to the overheat protection.*

 

 

Check sensor continuity.*

 

 

Check heat exchanger sealings and walls.*

 

 

 

Table 5

* By installer or service technician only.

26

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Contents SX NG SX LP What to do if you smell gasIndex For your safetyIndex FeaturingFCC Appliance details Features250 SX Specifications Technical data Combustion DimensionsSafety devices Gas typesDimensions and Minimum installation clearances DimensionsVenting Proper location for installing your heaterGeneral rules to follow for safe operation Combustion air requirements Mounting installationClearances Venting Room Minimum exhaust vent size and length Venting optionsAppliance details Room sealed installation Twin Pipe System Open combustion installation Single Pipe SystemDescription Minimum distance 720 607 Shown GAS Line SizingFor Natural GAS For LP GASGas line sizing Be Included in the Pipe SizingWater connections Plumbing Connections and Pressure Relief ValveOperating instructions For your safety read before operating your water heaterElectrical connections What to do if YOU Smell GASTo Turn OFF GAS to Appliance Operation instructions PowerTemperature selection Operation instructionsOperation instructions Setting the water temperature Flow/temperature chartsOperation Use of remote control accessoryReset button Program buttonMaintenance and service TroubleshootingUnbalanced pressure in water lines TroubleshootingTemperature balance valves Troubleshooting Display Cause Solution ChapterElectrical diagram Electrical diagramSX Functional scheme SX Functional schemeInterior components Interior components diagram and parts listInterior components diagram and parts list Components diagram Components DiagramParts list Description ReferenceSpecial adjustment for measuring and adjusting CO2 levels Adjusting the unitAdjusting Leave Program modePacking Protecting the environmentProtecting the environment ComponentsTwelve Year Limited Warranty Controlled Energy Corp