Main Fault Finding Procedures - Grant Vortex Pro Internal Combi Series Installation And Servicing Instructions

12.2 Main faULt finDinG pROCEDURES

a nO CEntRaL hEatinG - BUt hOt WatER OK
First, set the hot water switch to OFF
NO
Is the 'DEMAND' indicator
lit?
NO
YES
PCB is supplying voltage to
the CH pump but the pump
is not working.
Is the 'CH PUMP' indicator
lit?
YES
CH pump is not but there is
no circulation.
Is the 'CH PUMP' indicator
NO
lit?
YES
Is the 'CH PUMP' indicator
flashing?
Fast or slow flash
Fast flash
(twice per second):
Indicates a possible fault
with the 'flow' thermistor.
If the 'CH PUMP' indicator
continues flashing?
Slow flash
(once every 2 seconds):
Indicates a possible fault
with the PCB relay.
Is the 'BURNER' indicator
YES
lit?
Section 12: fault finding
Check programmer/timer and room thermostat are calling for heating.
Checking 'heating' switch is set to 'TIMED'.
Check electrical connections at the pump.
Check for 230V at the pump terminals.
Check if CH pump is stuck:
• Check for rotation of shaft/impellar.
• If still not operating, replace the CH pump.
Check both pump valves are open.
Check non-return valve on CH pump is operational (not sticking).
Check there are no air locks in the system (if removal of air is difficult - see additional
check list).
Check the non-return valve on the CH pump - is it stuck blocked open - check/rectify.
NOTE: CH return will be botter than flow if CH non-return valve is jammed open.
Check by closing one heating pump valve to stop circulation - does the store then come
up to temperature?
If the problem is not due to CH non-return valve - continue to the next check.
First, set boiler 'ON/OFF' switch to 'OFF'.
Wait 5 seconds
Then set 'ON/OFF' switch back to 'ON'.
Check CH 'flow' thermistor connection to the PCB.
Replace 'flow' thermistor.
Replace PCB
Is the burner firing?
If no: refer to 'burner not operating' procedure in Section 12.2 (C).
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