Glow-worm [F.29] fault codewhat it means and how to fix it

F.29 is "Fault: Flame loss" in Glow-worm's tables, and the Compact manual spells out the difference from F.28: this is "ignition and check faults during operation — flame has gone out". The boiler got as far as a stable flame and then the ionisation signal disappeared, so it closed the gas valve and, after its retries, locked out.

Glow-worm's causes are shorter than for F.28 and more about the boiler's surroundings than its parts: "gas supply temporarily stopped, flue gas recirculation, incorrect earthing of product, ignition transformer has spark failure", with "condensate siphon blocked" added on the Energy7 and the Compact adding a blocked air/flue pipe and a disconnected reference pressure pipe. Flue gas recirculation deserves a sentence, because it is the cause a householder can sometimes see: if the flue terminal is boxed in, damaged, or too close to a wall or a neighbour's terminal, the boiler breathes its own exhaust, the oxygen falls, and the flame fails after a few minutes of running — a boiler that lights fine and dies later, in windy weather especially, is often this.

On the Ultracom2 and Betacom2 the same F29 is "loss of flame during operation"; on the Ultracom, Flexicom and Ultrapower the number is F4. Glow-worm's homeowner page gives F.29 the same householder checks as F.28 — other gas appliances, meter credit, ice in an outdoor condensate pipe — and adds one cause of its own, the control electrode touching the burner.

1. 1

   Confirm the gas is on and the meter in credit, exactly as for F.28. A flame that was lit proves gas was present a moment ago, so if the meter is fine this step is quick.

2. 2

   Go outside and look at the flue terminal and the condensate pipe. A terminal with something leaning against it, a bird guard clogged with debris, or a plastic pipe with ice in it are all things Glow-worm list and all things you can fix without tools.

3. 3

   Reset once the way your guide describes. If the boiler lights and then drops out again after a few minutes, do not keep going — that pattern is recirculation, condensate or a failing component, none of which improves with repetition.

   Do not remove a flue guard or alter the terminal. Anything beyond clearing loose debris from outside is a Gas Safe job.