Operating instructions

ManualsBrandsViessmann ManualsBoilerWS3A

Fault

code in

the dis-

play

Const. Weath.-

comp.

System char-

acteristics

Cause Remedy

b4 X X Controls as if

the outside

temperature

was 0 °C

Internal fault Replace control

unit

b5 X X Control opera-

tion as per the

delivered con-

dition

Internal fault Replace control

unit

b7 X X Burner

blocked

Boiler codi ng

card fault

Plug in boiler c od-

ingcardorre-

place, if faulty

b8 X X Burner

blocked

Flue gas

temperature

sensor break

Check flue gas

temperature sen-

sor

bA X Mixer "Close" Communica-

tion fault –

extension kit

for heating

circuit M2

Check the exten-

sion kit connec-

tions and coding;

start the ex ten-

sion kit

bC X Control mode

without remote

control

Communica-

tion fault -

Vitotrol re-

mote control,

heating cir-

cuit A1

Check connec-

tions, cable/lead

and coding ad-

dress "A0"

bd X Control mode

without remote

control

Communica-

tion fault -

Vitotrol re-

mote control,

heating cir-

cuit M2

Check connec-

tions, cable/lead

and coding ad-

dress "A0"

bE X Control mode Vitotrol re-

mote control

incorrectly

encoded

Check remote

control DIP switch

setting (see

page 105)

bF X Con trol mode Incorrect

LON com-

munication

module

Replace the LON

communication

module

Fault codes (cont.)

74

Troubleshooting

5692 619 GB