281 Issue 1 - Service Manual - BX3
20
5.4 Three Flashes – Purge / Interwait
Purge / Interwait
•
Timer operating Eg:
•
Stat off during flame establishment time
•
Flame establishment time elapsed without flame
This failure can be caused by the unit failing to ignite at the start of its on time cycle without a
flame being detected.
Service Check List:
1. Check gas pressure or supply pressure
2. Check ignitor is in its right position
3. Check ignitor lead
4. Check gas valve loom and connections
5. Check flame sensors
6.
5.5 Four Flashes - Pressure Switch Lockout
Reason Pressure switch lockout
If the combustion fan pressure switch does not close shortly after the combustion fan has been
energised, the unit shall keep the combustion fan energised for 4 min, until either the pressure
switch closes or the call for heat is removed. If the pressure switch remains open longer than 4
minutes, the unit shall lockout. Once lockout occurs, the combustion fan turns off.
Service Check List:
1. Refer to Check List for 2 flash Pressure switch inactive
5.6 Five Flashes – Ignition Lockout
Reason:
Ignition lockout – failure to Ignite flame within the maximum allowable Ignition retry phase. There
is a maximum of 5 re-ignition attempts before the control board will lockout.
If a valid flame is undetected for the duration of the flame establishment or first safety time, the
unit shall enter lockout and flash 5 time fault code on the status LED. The safety time represents
the maximum time gas can flow without combustion occurring.
Service Check List:
1. Check the igniter high tension lead and terminal connections.
2. Check the igniter rod is clean
3. Check the igniter ceramic insulation is not cracked or damaged.
4. Check igniter is in its right location
5. Check gas pressure or supply pressure
6. Check gas valve loom and connections
7. Check if the control board is sparking
5.7 Six Flashes – Valve Fault Lockout
Reason:
