Glowworm Cxi Range and some Glowworm Hxi


Problem Solution
Inoperative Check power supply plug at M8, then check connection J13 which can be reversed look for 4 wires to the left then a space then a further wire to the right.

Hot water flow sensor can cause irregular faults, disconnect the flow sensor then retry for heating, if it works then replace the how water sensor

noise on low output

check low setting for correct CO2 ratio, can be droning from incorrect combustion

Burner door seal

The burner door seal has been replaced for a graphite seal, if the rubber one is fitted it may pass CO2/water onto spark generator and cause ignition problems

f9 fault resettable overheat stat back left hand corner may have tripped
water at back off appliance earlier models had problems with condensate collector leaking at back of heat exchanger, modified collector is available
blank display

1. check all connections are pushed in properly

2. disconnect fan at J4, if display returns change the fan

3. disconnect water pressure sensor if fitted, and if it shows F9 then blank when reconnected, change water sensor

f1 intermittent lockout

check spark gap set correct to 5mm (pound coin width), check for continous spark during ignition, generator can pulse and cause problems


Compact 75E & Compact 100E


Problem Solution
ignition problems low ignition pressure maye cause cross lighting issues, adjust to 6 mbars via potentiometer on PCB top Left hand corner. There is a modified burner available to overcome cross lighting problems
boiler on with no demand

domestic flow switch can stick on

fan and air pressure problems

plastic venturi in fan can melt


Compact 75P & Compact 100p


Problem Solution
Pilot problems/overheat The overheat thermostat is se to operate at 86 degrees C, which is very close to the normal operating temperature of 82 degrees C. The maximum temperature can be lowered to prevent pilot outage by adjusting potentiometer P2 on the PCB




Problem Solution
Explosive Ignition Modified electrode has been made with extended ceramic, these overcame problems with ignition
Ignition problems/combustion setting

Check gas valve setting, may have drifted or been incorrectly set, as a baseline turn throttle 8 full turns until boiler lights then reset as per manufacturers instructions

Fault code F70/F72

Usually after changing PCB or interface, check the DS number and modify where appropriate. This PCB fits several models so may need adjusting. Enter 2nd service level. Entering 1st service level as per Makers Instructions, but select password 35 instead of 96. Hold MODE for 5 seconds, screen will alternate between L2 and a number. Use + and - button to select 93. Press MODE button and the value will be displayed. Use + and - to alter the setting and MODE again to save. Set the DS number as follows;

12hX = 3, 15hx = 4, 18hx = 5, 24hx = 6, 30hx = 7, 18sx = 9, 30sx = 10. 24cx = 0, 30cx = 1, 35cx = 2.




Problem Solution
PCB replacement when changing the PCB the small interface board is redundant
boiler on no demand/pilot outage

check flow switch is not stuck on, disconnect wire to prove, can spray into valve with WD40 from underneath to lubricate and free switch mechanism

pump running continuously

pull of lead to heating thermister, if pump stops then change thermister





Problem Solution
fault code f13 before replacing PCB check the low voltage components/harness, any short to earth will give you f13 fault. Check NTC readings and remove from pipework to make sure there's no path to earth
to check flow switch operation

press and hold light switch for 5 seconds for menu

press the water plus button until 07 displayed

open a hot water tap, the display will now give the flow rate in litres divided by 10, eg 130 on the display = 13 l/min.