How to mend Glow-worm F

I have a 30cx glowwarm that is showing F4 as fault.I have no hot water?

Home heating systems?

GS 24i junior boiler timer broken?

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I have moved into a flat am dissabled carnt get heating on unit flashing F1?

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boiler Glow-worm30cxi 30cxi not working?

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Suprima 50?

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My radiators not heating up?

Central heating not working?

My central heating is not working?

radiators hot when water turned on?

How can I fix my glow worm flexicom 30cx ?

BMU error code?

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What can I do about a Glow-worm Flexicom 30cx fault code F11?