Mini SE/HE

Boiler in standby mode - no call for heating or hot water  
Indicating Central Heating operation Not fault with boiler external controls calling for heat
Indicating Domestic Hot water operation Not fault with boiler hot water tap open. If customer confirms no tap open book callout
Boiler in frost protection mode Boiler will go into frost protection mode if temperature drops below 4 deg C
DHW operation - Excessive temperature in primary circuit  
Faulty Central heating thermistor Book callout
Faulty DHW thermistor Book callout
Faulty flue thermistor Book callout
Faulty primary circuit - lack of water flow through boiler Check pressure gauge - 1-1.5 bar/check for air in system - bleed radiators etc. If all checked book callout
Faulty air pressure switch Check black plugs are fitted on top left of boiler(soemtimes knocked off during installation) - if ok book callout
Boiler failed to ignite - ignition lockout Check gas supply, if OK book callout
Overheat thermostat lockout Attempt to reset boiler by press red reset button. Overheat condition may occur due to air in system or poor circulation. - If all OK book callout
Flue thermistor lockout Probably due to lack of servicing, condesate backing up into boiler. If boiler recently installed or has been serviced - book callout
Lack of power supply or faulty PCB Check fused spur - if OK book callout
Faulty PCB Book callout