6 | P a g e
• You can force the pump by removing PWM cable at the pump to allow the 230v cable to power the
pump at full speed.
• To do this, ensure safe electrical isolation and then use a 4mm electrical screwdriver to push down
the clip below the PWM connector and gently pull the connector out. Re-establish power to the
boiler and the pump should run at full speed.
7. Confirm 230v from the PCB connector X9 pin 1 & X10 pin 2. If no voltage, replace PCB.
8. Check 230v supplied from the PCB to the pump connector. If voltage at pump connector, replace pump.
9. If no voltage at pump connector, use a multimeter to check the wiring harness for continuity from the PCB
via connector X9 pin 1 & X10 pin 2, whilst checking connectors are tight and free from damage or corrosion.
Replace as required.
10. If 230v side ok, check the pump PWM via the 3-wire cable connection to the pump on PCB connector X1 pins
1&2:
• with the pump off the voltage is +/- 5VDC.
• 39% load the voltage is +/- 3VDC.
• 61% load the voltage is +/- 1.9VDC.
• 100% load the voltage is +/- 0.24VDC.
11. If the above voltages are correct, and the pump does not operate, replace the pump.
12. If the voltages are incorrect, replace the PCB.
13. Check expansion vessel pressure is set correctly as per the manufacturer’s instructions.
14. Check expansion vessel flexi hose is correctly connected with no kinks or blockages.
15. Check the boiler for any blockages or restrictions.
16. After checking all the above points, switch off the power and back on again, allow the boiler to run
automatically through the automatic venting program.
17. If the fault persists, replace the PCB.
105 Description: Venting program active.
Cause: No fault – venting program will run for 7 minutes.
110 Description: Safety temperature exceeded.
Cause: Temperature rise too fast, possible sensor fault or circulation.
1. Check the system for an external heat source such as solar which may affect the return temperature.
2. Confirm flow and return temperatures using the A menu, A0 &A1.
3. Check T1 and T2 resistances in line with temperatures from flow and return temperatures found on page 67.
• Take resistances at the connector X4 on the PCB pins 1 & 2, and pins 3 & 4. This checks the wiring
harness continuity and connectors at same time.
• Check wiring connectors are not loose or corroded.
• Disconnect the connector from PCB to ensure no additional resistances are given through the PCB.
• If readings incorrect, take resistance reading direct from sensor & replace sensor or wiring harness
as required.
*Note sensors may need cleaning and not always replaced*.
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