Normal Operation - Keston C45 Installation And Servicing Instructions

WD536
5.2

NORMAL OPERATION

The C45, C40P and C55(P) boilers feature a user display which shows actual flow temperature at
all times (the last two digits of the display) and a status number (the first digit) which identifies
what the boiler is doing at any given time. The table below shows the range of status codes which
will be displayed as part of normal boiler operation:
NORMAL OPERATION CODES
Display Meaning
0 nn Boiler in standby waiting for demand signal
1 nn Boiler is running fan prior to attempting ignition
2 nn Boiler has opened gas valve and is sparking at ignitor
3 nn Boiler is alight and running in response to a demand from central heating (i.e. SL1)
4 nn Boiler is alight and running in response to a demand from DHW (i.e. SL2)
5 nn Temporary mode whilst boiler is adjusting internal settings
6 nn Burner is off because the boiler is up to temperature
7 nn Boiler pump is in Central Heating overrun mode (2 mins)
8 nn Boiler pump is in DHW overrun mode (2 mins)
A nn Temporary mode whilst boiler is adjusting internal settings
5.3 FAULT MODES
5.3.1 Automatic Lockout Avoidance
The boiler will react to adverse conditions in two ways. If the fault is not severe, or is not
persistent, the boiler will halt (or block) operation for a set time before it attempts to fire again.
During this block time the block code will be displayed, alternately with the code "9 nn", where nn
is the boiler flow temperature.
BLOCK CODES
Display Reason for block
B 18 Flow temperature exceed 95
B 19 Return temperature exceeded 95
B 24 Return temperature exceeded flow temperature. Check pump direction on boiler
and any external pumps. Check wires on flow and return thermistors are not
crossed.
B 25 Flow temperature climbing too quickly. Possible air lock or circulation blockage
B 26 Low water pressure
B 28 No signal from fan. Possible fan disconnected or faulty.
B 29 Incorrect signal from fan. Possible fan faulty.
B 30 Difference between flow and return temperatures too high. Check water circulation
B 65 Waiting for fan to start
Installation & Servicing Instructions
Chapter 5 : Fault Finding
QUICK REFERENCE
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The Keston C45, C40P, C55 & C55P
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