12 Fault Finding
38
Fault Finding
B. No Hot Water - but Central Heating OK
First - Set Heating switch to OFF
Is the “DEMAND” NO Check programmer is calling for hot water.
indicator lit? If no programmer is fitted: Check ‘Hot Water’ switch is set to
‘CONSTANT’.
NO Check ‘Heating’ switch is set to ‘TIMED’.
Is the “FLOW SWITCH” NO Check hot water tap is open.
indicator lit? Check water flow rate is at least 3 ltr/min.
Cannot achieve 3 ltr/min Check the mains stop tap open fully.
Check cold water isolation valve in boiler is open.
Check if the flow restrictor (located in the cold water isolation valve)
is clear.
If not, clean restrictor or remove from valve.
NOTE: No flow restrictor is fitted to the Combi 36e model.
Is the water pressure OK? Check standing water pressure.
Low water pressure = low 2 bar minimum standing pressure required
water flow rate
Check running (dynamic) pressure.
1 bar minimum dynamic pressure required.
If pressure is OK. Check for blockage in plate heat exchanger unit.
NOTE: In hard water areas scale will be produced that can block the
plate heat exchanger if no anti-scale protection has been installed.
Refer to Section 5 for further details.
If plate heat exchanger is OK. Check flow switch is correctly positioned: the arrow (on flow switch
body) must point in direction of flow (i.e. towards front of boiler).
Check switch is free to operate: Close cold water isolation valve, remove
flow switch from pipe work – manually operate switch paddle to check.
Remove any debris/blockage from the pipework body or switch paddle.
Check for electrical continuity between flow switch terminals when
switch is closed.
No continuity – replace flow switch.
Check for 230V at flow switch terminals.
No 230V – check connections at PCB.
If still no 230V – replace PCB.
Is the “FLOW YES Flow switch is activated.
SWITCH” indicator lit? Continue to the next check.
Is the “DHW PUMP” NO Continue to next check.
indicator lit?
Is the “DHW YES First – set boiler ‘On/Off’ switch to ‘OFF’.
PUMP” flashing? Fast or Slow flash Wait 5 seconds.
Then set ‘On/Off’ switch back to ‘ON’.
If the “DHW PUMP” Fast flash (twice per second): Check DHW ‘Store’ thermistor connection to PCB.
indicator Continues Indicates a possible fault Replace ‘Store’ thermistor.
flashing. with the ‘Store’ thermistor.
Slow flash (once every 2 Replace PCB.
seconds): Indicates a possible
fault with the PCB (relay).
To Next Page
Loading...
Need help?
General