Potterton Gold HE A Range Installation & Service Instructions Manual page 57

I
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
J
1.
Overheat thermostat operated or
faulty, i.e. continuity across
thermostat terminals
YES
K
Is there 230V at:
1.
Motor 3-way valve
2. PCB - X3 connector terminals
5 & 6 central heating mode
5 & 7 domestic hot water mode
YES
Change pump supply cable
L
1.
Fan connections correct at fan.
PCB - X401 connector terminals 5,6,7 & 8
M
1.
Temperature sensors faulty.
Cold resistance approximately
10kΩ @ 25° C (CH sensor)
20kΩ @ 25° C (Flue sensor)
(resistance reduces with increase in temp.)
2.
If pump is running the heat exchanger could be
obstructed
© Baxi Heating UK Ltd 2008
Allow to cool. Continuity
NO
across thermostat terminals
more than 1.5 ohm
Replace PCB
YES
NO
YES
NO
YES
18.0 Fault Finding
YES
Replace PCB
NO
Replace flame sensing electrode
YES
Replace motor 3-way valve
Replace PCB
Replace fan
Replace sensor
Replace heat exchanger
Replace safety thermostat
57