Glow-worm F1: ignition failure and what precedes it
F1 tells you the burner tried to light and the boiler never confirmed a flame within the allowed window. It is one of the more common lockouts on Glow-worm appliances, and it responds well to a methodical check rather than parts-swapping.
How we read a Glow-worm F1 fault on site
Working gas pressure is measured at the appliance first, since undersupply produces exactly this fault and costs nothing to rule out. The condensate trap is inspected next, particularly in cold weather, followed by the electrode gap and spark lead condition against Glow-worm's published figures. Combustion analysis confirms any repair rather than relying on how the flame looks by eye.
Who should undertake the work
- Gas appliance work must be completed by a suitably qualified Gas Safe engineer
- Oil appliance work should be completed by a suitably qualified OFTEC technician
- Jamie Crawford Heating states both Gas Safe and OFTEC registration
Detail that affects your quote for a Glow-worm F1 fault
- Working gas pressure is measured before any part is considered
- Condensate trap blockages spike in cold weather specifically
- Electrode gap is checked against Glow-worm's stated tolerance
- A flame that looks fine by eye can still be badly seated
- Combustion analysis verifies the repair, not a visual check alone
Questions we get asked
- Could low gas pressure from the street affect this?
- It can — undersized or shared supply pipework sometimes causes marginal pressure that only shows up under full boiler demand.
- Is F1 dangerous to keep resetting?
- Beyond two attempts, yes — it means the flame cannot be reliably proved and forcing further attempts is unsafe.
Related help pages
- Potterton fault codePotterton E125: no ignition detected on a Promax or Gold
- Cycling symptomBoiler turning on and off repeatedly through the day
- Ideal fault codeIdeal Logic L2 lockout: flame loss on a Logic or Vogue
- Ideal fault codeIdeal F1: low pressure lockout on a Logic or Vogue
- Property typeHeating large rural houses: zoning and boiler capacity
- Office servicingBoiler servicing for small offices
Services that cover this
Where we deal with this
Sorted quickly: a Glow-worm F1 fault
Where this leaves you: Pressure, condensate, electrodes, combustion check — in that order F1 is usually solved in a single visit.
Use the enquiry form to describe the appliance, fault code and what changed before the problem started.
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