3 nn Boiler burning for zone 1
4 nn Boiler burning for zone 2
5 nn Temporary mode whilst boiler adjusts its internal settings
6 nn Burner off because required temperature has been reached
7 nn Boiler at end of heat request from zone 1
8 nn Boiler at end of heat request from zone 2
A nn Temporary mode whilst boiler adjusts its internal settings
9 nn Boiler off due to unexpected problem. The boiler will attempt to
re-fire from this mode. In this mode the display will alternately
flash “9 nn” and “b xx” where the “xx” has the following meaning:
b 18 Boiler ran too hot, > 95
O
C flow temperature
b 19 Boiler ran too hot, > 95
O
C return temperature
b 24 Boiler circulating in reverse. Check external pump
b 25 Boiler rising in temperature too quickly. Check for system
blockages
b 26 Low water pressure. Top up system pressure and check
for leaks.
b 28 No signal from fan, possible stuck fan motor.
b 29 Fan running when not required.
b 30 Circulation too slow. Check system for blockages
b 65 Waiting for fan to start. Possibly stuck.
All of the above displays, up to “A nn” indicate normal boiler operation. Display “9 nn”
indicates a delay in boiler operation but will not stop boiler operation.
Precautions
Care must be taken at all times to ensure that no blockage or obstruction is present
in the condensate drainage line. In addition the air intake and flue exhaust terminals
of the appliance must be free of obstruction at all times.
Frost Protection
The C40 and C55 have an integral frost protection thermostat. However, care should
also be taken to ensure that any exposed pipework is adequately insulated to
prevent freezing.
Error Codes
In the event of a fault causing a boiler shutdown the display will show an error
message “E nn”.
Internal electronics error - rest or replace control boxE 11
Power has been reset whilst boiler was in lockoutE 04
Gas valve faulty or not connectedE 03
No ignition after restart. Check gas supply, gas valve operation and ignitor electrode
spark generation
E 02
Flame detected when not expected. Check boiler earth and probe condition.E 00
Description of faultDisplay
WD274/1/2002
page iii
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