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Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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I have a Glow Worm Flexicom 12hx that was been giving f4 and

Customer Question

Hi Marc,
I have a Glow Worm Flexicom 12hx that was been giving f4 and f22 errors since I moved into my house 3 years ago. I get it serviced every year and last year it was particularly bad so we had an engineer have a look but he couldn't find a root cause, and chalked it up to needing a further service. So had the service and sure enough it's been fine ever since. Then yesterday out of the blue f4, reset the system and it worked fine, today when I got up this morning f4, another when I got home from work, and now have had 4 in the space of an hour followed by an f22.
I'm guessing this has something to do with the sudden drop in the outside temp over the last day.
Thanks in advance
Submitted: 1 year ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 1 year ago.

You may find that you have a slight crack in the ignitor and the cold weather is affecting it.

You may want to try a new ignitor as F4 is flame failure and F22 could be low water pressure or lack of heat when running

Customer: replied 1 year ago.
Hi Andrew,Can you explain in a bit more detail as I am a complete novice when it comes to most of plumbing, (was happy simply when I unblocked a toilet!) Should a crack in the ignitor not have been picked up during the service / would this develop in 5 months since the last service?
Expert:  Andrew Smith replied 1 year ago.

This would be a hairline crack and may not even be visible.

The crack may increase in size with heat/cold and when it does then the spark will go to earth rather than through the ignition electrode.

It would be interesting if you can see how it fails.

Customer: replied 1 year ago.
Thing is it does seem to ignite, heats up for a bit but only to the low 50'sC, whereas the heating temp is set to 80C, then will cut out and show f4, by the time I've noticed heating temp is down to low 30'sC.
Expert:  Andrew Smith replied 1 year ago.

It could be the ignitor then, failing when hot and wil not reset until cold again.

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