Baxi Bermuda BBU 15 HE Installation & Servicing Instructions Manual page 37

H
1.
Check the gas supply pressure:
For Natural Gas greater than
10 - 11 mbar
2. Check and correct if necessary
1. The mechanical set of the gas valve
(CO2 values - see instruction)
2. Flame sensing electrode and lead connections
3. Flame sensing electrode position
Flame current should be more than 0.5 μA
I
Overheat Thermostat or
Condensate Safety Float Switch
operated or faulty
J
Press the Service Reset switch
for 5 seconds
K
Fan connections correct at fan.
PCB - X401 connector terminals 5,6,7 & 8
L
1.
Temperature sensors faulty.
Cold resistance approximately
10kΩ @ 25° C (CH sensor)
(resistance reduces with increase in temp.)
2.
If pump is running the heat exchanger could be
obstructed
IMPORTANT:There is no limit to the number of repeated 'Service Reset'
operations but the Boiler Control must be refreshed by 'Restoring Boiler
Control Default' as described on p.34 following the final 'Service Reset' and
© Baxi Heating UK Ltd 2009
YES
NO
Allow to cool. Continuity
across thermostat terminals
more than 1.5 ohm
NO
Continuity across plug
terminals at 3 & 4 of connector
X401 more than1.5 ohm
YES
Condensate drain system fault
NO
Replace Safety Float Switch
or wiring
Restore Boiler Control defaults
YES
NO
Replace sensor
YES
before the Boiler Control reset is re-used.
12.0 Fault Finding
Replace PCB
Replace flame sensing electrode
YES
NO
YES
Replace fan
Replace heat exchanger
Replace Safety Thermostat
Replace PCB
Check condensate system
and Pump
37