Worcester Bosch Boilers
Worcester Cdi Standard Efficiency
Worcester Bosch 24Cdi, 28Cdi, 35Cdi
| Problem | Solution |
| Common Lockout, (Radiator light flashing) | Moisture in 21 way low voltage connector on PCB Faulty sensing electrode/lead Sticking gas valve, or incorrectly set low gas |
| Air Pressure Problems (Tap light flashing) | Damaged air pressure tubes Sticking or slow fan, sticking air pressure switch If flue is over 1m check restrictor has been removed
|
| Poor hot water | Plate heat exchangers can block with magnatite, also check hot water sensor for correct resistance. Diverter valve can pass down heating pipe when in hot water, giving poor hot water, requires new valve or service kit inside valve |
| No heating | Central Heating Knob Spindle can snap on PCB |
| Overpressurising | Earlier plate heat exchangers can pinhole internally, causing mains pressure to go into central heating resulting in 3bar pressure on gauge and discharge from PRV Also check expansion vessel diaphragm has not perished |
Worcester Si II, Si2 Range
Worcester 24 Si2, Worcester 24 SiII, Worceseter 28 Si2 SiII, British Gas RD628
| Problem | Solution |
| Lockout light flashing | PCB's are prone to failing and causing lockout, once all other tests have been carried out, suspect PCB |
| PCB identification | There are two PCB's on these models, dependant to the gas valve fitted, the earlier model has the solenoids at the rear if the gas valve, the later model the solenoids are at the front. |
| Code Plug | Remember to remove the small module when changing the PCB as it won't work without it! |
Worcester 240 RSF
| Problem | Solution |
| Central heating stuck on high gas, overheating | Check diverter valve microswitches, these affect heating if faulty |
| Boiler on no demand | Pump over run faulty |
| Poor water | Diverter valve can pass to central heating when in hot water mode, feel central heating pipes to confirm passing when running hot water |
Worcester 24i Junior
| Problem | Solution |
| No gas but sparking | Check low water pressure switch for continuity, aswell as overheat. These are wired in series and cut power to gas valve. |
| Intermittent faults | Poor flame/lockout, PCB's can fail meaning fan stops suddenly when in operation, flames then baffle momentarily and appliance locks out |
| Condensate in APS tubes | Deflector kit available to deflect cold air away from AP tubes |
Worcester RSF
Worcester 24i RSF, Worcester 28i RSF
| Problem | Solution |
| Common lockout | Low gas/ignition pressure not checked Faulty ignition/flame sensing electrodes Sticking Gas valve |
| Air pressure problems | Older appliances had a black air pressure switch which was problematic, new replacement is improved switch Check for moisture in tubes, auto air vent can leak and drip water into tubes |
| No central heating | User has snapped control knob, check stalk onto PCB |
| Boiler dead | Check overheat stat has not operated on top left hand corner of appliance |
Worcester 280 RSF
| Problem | Solution |
| Intermittent Faults | CH/primary sensor can error when hot, please check/change before suspecting driver PCB |
| No heating | Synchron faulty in diverter valve, it is possible to change just the motor rather than the complete diverter valve, check to see if the valve is motoring from A to B, and then operate the manual lever at the bottom, if the valve holds open once manually operated, suspect the motor |
Worcester 350
| Problem | Solution |
| Central Heating fails to relight | Time delay of 90 seconds on driver board before heating reignites, may be faulty |
| Heating coming on with water | Non return valves can stick on pumps |
| Hot water ok, heating problems | Fan resistor may be faulty, should restrict fan to slower speed by reducing voltage to 170Volts, may be going open circuit |
Worcester Greenstar i Junior
Worcester Greenstar 24i Junior, Worcester Greenstar 28i Junior
| Problem | Solution |
| Unable to reset lockout | Water on gas valve due to frozen/blocked condensate, dry out wires and then try to reset again |
clunk/noisy after demand |
Internal bypass can be noisy after demand |
| Ignition issues after new PCB fitted | Confirm the correct PCB has been fitted, there are several versions, mainly one to fit those boilers with on/off switch, and one without the on/off switch. If the incorrect PCB has been fitted, there may be a weak spark, or no gas |
| Overheat lockout unable to clear | Early models had an air pressure switch wired in series with overheat stats, check flue for blockages or suspect air flow problem |
| No blue fascia light LED but appliance operating | Press spanner button for approx 11 seconds, blue LED should light up, press eco button, press spanner button until light goes out, blue led should now re illuminate |
| Random water leaks underneath | Water meters can cause excess back pressure at appliance, due to the non return valves at the meter, remedy by installing a mini remote expansion vessel |
Worcester Greenstar Cdi
Worcester Greenstar 25Cdi, Worcester Greenstar 27 Cdi, Worcester Greenstar 30 Cdi, Worcester Greenstar 31 Cdi,
Worcester Greenstar 35 Cdi, Worcester Greenstar 37 Cdi, Worcester Greenstar 40 Cdi, Worcester Greenstar 42 Cdi
| Problem | Solution |
| FO fault code | Check HT leads, electrode leads are not trapped or shorting to earth |
| SE code in display | Service Engineer visit reminder, may not have been reset on last service, not a fault, just a reminder. Press/hold spanner button for 10 seconds, press/let go eco button until SA (5A) displayed, press/let go chimney sweep button,press/let go eco button, press/hold chimney sweep until brackets appear, press/hold spanner button to exit. Done! |
| Pressure Loss | Heat cell can leak internally, central heating water leaks down condensate, disconnect condensate and observe for drips to test |
Worcester Greenstar HE Plus ZWB
| Problem | Solution |
| C1 fault code | Check for 230 VAC at blue white fan connector, if present, change fan |
| Pressure Loss | Heat cell can leak internally, central heating water leaks down condensate, disconnect condensate and observe for drips to test |
Worcester Highflow 400
| Problem | Solution |
| poor hot water/noisy on hot water | plate heat exchanger blocked there is a filter on some models, in the top manifold, behind a brass plug held in by a plate and screw. these can block easily |
| overheating | as per manufacturers, there is a dip tube kit to fit into the return make sure overheat phial is fully pushed home, too much capillary tube left in the combustion chamber can result in nuisance overheating |