Worcester boilers troubleshooting

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

ProblemCauseRemedy
Desired room temperature is not reachedThermostatic radiator valve(s) set too lowIncrease thermostatic radiator valve setting(s)
Room thermostat set too lowIncrease room thermostat setting
Temperature control for flow on boiler set too lowIncrease flow temperature control setting
Air trapped in heating systemBleed radiators, if fitted to a sealed system recharge heating system
Desired room temperature exceeded by large amountRadiators are too hotTurn down thermostatic radiator valves / room stat
Temperature rises instead of fallingClock is incorrectly setCheck setting
No display or display unit does not respondMomentary power failureSwitch off appliance at master switch, wait a few seconds then switch on again
Hot water temperature too lowHot water tank temperature set too lowCheck setting
Hot water not in timed period on the programmerCheck programmer settings
Temperature control on boiler set too lowCheck setting

Worcester 5070 boilers troubleshooting

SYMPTOMPOSSIBLE CAUSECHECK/REMEDY
Boiler does not fire and burner lockout lamp is not illuminatedThere 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 illuminatedThe 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

ProblemCauseRemedy
Desired room temperature is not reachedThermostatic radiator valve(s) set too lowIncrease thermostatic radiator valve setting(s).
Temperature control for central heating flow on boiler set too lowIncrease central heating flow temperature control setting
Low temperature setting on the room thermostatIncrease 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 highThermostatic radiator valve(s) are set too highTurn down thermostatic radiator valves/room thermostat
Room thermostat is set too highReduce central heating temperature by turning down the Central Heating control on boiler
Heating stays on for too longClock is incorrectly setCheck setting and adjust
Hot waterTemperature set too low on cylinder thermostat control.
temperature too lowAir 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 highTemperature set too high on cylinder thermostat control.Check setting and adjust

Worcester Greenstar utility 32-50kW boilers troubleshooting

PROBLEMCAUSEREMEDY
Pulsation on startFlue draught incorrectCheck flue draught
Combustion settings incorrectSet up as in installation instructions
Faulty nozzleReplace nozzle
Intermittent lockoutBad electrical connectionCheck control box connections
Intermittent flame detection faultSee flame detection fault
DowndraughtExtend flue or fit a downdraught cowl
Burner motor fails to operateFaulty motor or electrical supply to motorCheck motor across mains supply
Control box faultReplace control box
Flame detection faultPhotocell filmed overClean
Photocell faultyReplace
Control box faulty
Air adjustment faultIncorrect CO2Set up as in installation instructions
Air in pumpBleed pump
Nozzle blockedReplace nozzle
Faulty pump or driveReplace
Faulty mechanical shut off valveClean or replace
Ignition failureElectrode settings incorrectSet up as in installation instructions
Faulty ignition transformerReplace
Open circuit ignitionCheck and replace electrodes or high tension leads if necessary connections not properly made
Faulty control box or electricalCorrect electrical control box connections
BURNER FAILS TO STARTFaulty boiler thermostatCheck by linking out high limit and control thermostats
Faulty control boxReplace
HIGH SMOKE NUMBERFaulty nozzleReplace nozzle
Air intake blockedCheck & clear air intake
Incorrect combustion settingsSet up as in installation instructions
Oil pressure incorrectAdjust to correct pressure
Incorrect components used on combustion headCheck with installation instructions
Noisy operationPump noise from air in pump or worn pumpBleed air from pump or replace pump
Worn motor bearingsReplace motor
Fan out of balanceReplace fan
BoilingFaulty boiler thermostatTake out of circuit to check
Thermostat bulb not fully home in pocketEnsure bulb is pushed fully home
Short CyclingBoiler rating incorrectCorrect boiler rating
Boiler thermostat differential incorrectReplace boiler thermostat
External controls not operating correctlyCheck and correct external controls
OIL SMELLSBlocked flue, fumes on startupCheck flue with gauge
Oil soaked hearth, faulty burner operation, numerous lockoutsRectify burner operation and lockouts
Odour in boiler room, oil leaks from pipework, flexible hoses connectionsRectify oil leaks, replace components if necessary