14 | P a g e
4. On combi’s, the diverter valve operation may be faulty, check as follows:
• Safely isolate boiler from electrics.
• Remove the motor from the three-way valve and see if the cartridge moves up and down.
• If this doesn't move smoothly and seems to be sticking, replace the cartridge.
5. Check system pipework configuration correct.
6. Ensure all valves on the system and boiler are open.
7. Ensure all air is vented out of the boiler and system.
8. Check system pipework and filters for any blockages or restrictions.
9. Check all installation components are functioning correctly (mixing pumps and 2-way valves, etc.).
10. In the case of a combi, check the plate heat exchanger is not blocked.
11. Check for Voltage at the pump:
• You can force the pump by removing the PWM cable to allow 230v cable to power pump at full
speed.
• If pump does not run via above test check, check 230v across PCB connectors X9, pin 1, and X10
pin 2. If no voltage present, replace PCB.
• If voltage present check pins on pump PWM connector are not bent – straighten to fix if
required, and check continuity of wiring harness.
• Check the pump PWM via the 2-wire cable connection to the pump on PCB connector X1 pin
1&2:
1. with the pump off the voltage is +/- 9VDC.
2. On pump startup the voltage is +/- 1VDC.
3. Pump overrun approx. 4.5VDC
4. Normal running approx. 4.3VDC
• If above DC voltages are incorrect, replace PCB.
• If voltage to pump and all other checks are ok, replace pump.
*Note * If plastic pipes are used, they must be barrier pipes & UFH must comply with DIN4726-4729. If this is not the
case, system separation must be provided as these pipes are porous & will allow air into the system.
164 Description: iR boiler Flow error.
Cause: flow switch has an open connection during the operation of the boiler or before starting up. Usually, system
related.
1. Check the pump for air and vent the system if required.
• Use the boiler air purge to assist by turning off the power at the fused spur for 5 seconds and
then re-establish the power.
2. Check external pump operating properly/strong enough.
3. Check auto air vent is operating correctly and not contaminated with sludge.
4. Check all isolation valves on boiler and system are open.
5. Check system design.
6. Check system for blockages.
7. To check the flow switch, disconnect it from the boiler and using a multimeter across the connections, check
for continuity when making the switch and OL when switch breaks. Only replace the flow switch when all
the above has been checked and confirmed.
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