The reality is that 90% of faults occurring in heating boilers are revealed during external examinations. About 9% are eliminated by cleaning and lubrication, and only about 1% account for serious diagnostic and repair work. The troubleshooting table below describes the most common causes of breakdowns. Please, check the signs described in it against those you are observing and find a solution.
Worcester 1218 boilers troubleshooting
| Problem | Cause | Remedy |
|---|---|---|
| Desired room temperature is not reached | Thermostatic radiator valve(s) set too low | Increase thermostatic radiator valve setting(s) |
| Room thermostat set too low | Increase room thermostat setting | |
| Temperature control for flow on boiler set too low | Increase flow temperature control setting | |
| Air trapped in heating system | Bleed radiators, if fitted to a sealed system recharge heating system | |
| Desired room temperature exceeded by large amount | Radiators are too hot | Turn down thermostatic radiator valves / room stat |
| Temperature rises instead of falling | Clock is incorrectly set | Check setting |
| No display or display unit does not respond | Momentary power failure | Switch off appliance at master switch, wait a few seconds then switch on again |
| Hot water temperature too low | Hot water tank temperature set too low | Check setting |
| Hot water not in timed period on the programmer | Check programmer settings | |
| Temperature control on boiler set too low | Check setting |
Worcester 5070 boilers troubleshooting
| SYMPTOM | POSSIBLE CAUSE | CHECK/REMEDY |
|---|---|---|
| Boiler does not fire and burner lockout lamp is not illuminated | There is no demand for heat from external control equipment | • Check the programmer is programmed for hot water and/or central heating and reprogramme if necessary. |
| • If the boiler is programmed for central heating, check the room thermostat is turned on. | ||
| • Check any other control devices fitted. | ||
| There is no demand for heat from the boiler temperature control thermostat. | • Turn the temperature control knob to maximum. | |
| The automatic reset overheat thermostat has operated. | • If the boiler is hot allow time to self reset. | |
| Manual reset overheat thermostat has operated. | • Press the reset button. | |
| There is no electricity supply to the boiler. | • Check power supply is switched on. | |
| • Check the external power supply fuse. | ||
| Boiler does not fire and burner lockout lamp is illuminated | The boiler has attempted to fire, but has gone to lockout. | • Remove the appliance front cover and depress the lockout reset button on the burner. |
| • Check the level in your oil tank and replenish if necessary. |
Worcester Greenstar Danesmoor External Regular ErP boilers troubleshooting
| Problem | Cause | Remedy |
|---|---|---|
| Desired room temperature is not reached | Thermostatic radiator valve(s) set too low | Increase thermostatic radiator valve setting(s). |
| Temperature control for central heating flow on boiler set too low | Increase central heating flow temperature control setting | |
| Low temperature setting on the room thermostat | Increase settings on room thermostat | |
| Air trapped in heating system (System model) | Bleed radiators and re-pressurise the heating system | |
| Low system water pressure (System model) | Re-pressurise the system, refer to page 8 | |
| Desired room temperature is too high | Thermostatic radiator valve(s) are set too high | Turn down thermostatic radiator valves/room thermostat |
| Room thermostat is set too high | Reduce central heating temperature by turning down the Central Heating control on boiler | |
| Heating stays on for too long | Clock is incorrectly set | Check setting and adjust |
| Hot water | Temperature set too low on cylinder thermostat control. | |
| temperature too low | Air trapped in heating system (System model) | Bleed radiators and re-pressurise the heating system |
| Low system water pressure (System model) | Re-pressurise the system, | |
| Hot water temperature too high | Temperature set too high on cylinder thermostat control. | Check setting and adjust |
Worcester Greenstar utility 32-50kW boilers troubleshooting
| PROBLEM | CAUSE | REMEDY |
|---|---|---|
| Pulsation on start | Flue draught incorrect | Check flue draught |
| Combustion settings incorrect | Set up as in installation instructions | |
| Faulty nozzle | Replace nozzle | |
| Intermittent lockout | Bad electrical connection | Check control box connections |
| Intermittent flame detection fault | See flame detection fault | |
| Downdraught | Extend flue or fit a downdraught cowl | |
| Burner motor fails to operate | Faulty motor or electrical supply to motor | Check motor across mains supply |
| Control box fault | Replace control box | |
| Flame detection fault | Photocell filmed over | Clean |
| Photocell faulty | Replace | |
| Control box faulty | ||
| Air adjustment fault | Incorrect CO2 | Set up as in installation instructions |
| Air in pump | Bleed pump | |
| Nozzle blocked | Replace nozzle | |
| Faulty pump or drive | Replace | |
| Faulty mechanical shut off valve | Clean or replace | |
| Ignition failure | Electrode settings incorrect | Set up as in installation instructions |
| Faulty ignition transformer | Replace | |
| Open circuit ignition | Check and replace electrodes or high tension leads if necessary connections not properly made | |
| Faulty control box or electrical | Correct electrical control box connections | |
| BURNER FAILS TO START | Faulty boiler thermostat | Check by linking out high limit and control thermostats |
| Faulty control box | Replace | |
| HIGH SMOKE NUMBER | Faulty nozzle | Replace nozzle |
| Air intake blocked | Check & clear air intake | |
| Incorrect combustion settings | Set up as in installation instructions | |
| Oil pressure incorrect | Adjust to correct pressure | |
| Incorrect components used on combustion head | Check with installation instructions | |
| Noisy operation | Pump noise from air in pump or worn pump | Bleed air from pump or replace pump |
| Worn motor bearings | Replace motor | |
| Fan out of balance | Replace fan | |
| Boiling | Faulty boiler thermostat | Take out of circuit to check |
| Thermostat bulb not fully home in pocket | Ensure bulb is pushed fully home | |
| Short Cycling | Boiler rating incorrect | Correct boiler rating |
| Boiler thermostat differential incorrect | Replace boiler thermostat | |
| External controls not operating correctly | Check and correct external controls | |
| OIL SMELLS | Blocked flue, fumes on startup | Check flue with gauge |
| Oil soaked hearth, faulty burner operation, numerous lockouts | Rectify burner operation and lockouts | |
| Odour in boiler room, oil leaks from pipework, flexible hoses connections | Rectify oil leaks, replace components if necessary |