When temperatures drop, it’s common for homeowners to suddenly find the heating not kicking in just when it’s needed most. If your boiler won’t fire up during freezing weather, don’t panic—many issues have simple explanations you can safely check before calling out an engineer. This long-form guide walks you through practical steps, winter readiness checks, and the meaning of common UK boiler fault codes often seen in Bordon, Whitehill, Liphook, Alton, Farnham and surrounding GU35, GU34 and GU9 areas.
Quick checks you can do now
Before assuming the worst, run through these simple homeowner-safe checks. Many “boiler not firing” cases turn out to be minor issues.
- Check your thermostat is set higher than room temperature.
- Ensure the heating and hot water schedules are active.
- Confirm the boiler display is on and not in standby mode.
- Look for an error or fault code on the display.
- Reset the boiler once following the manufacturer’s instructions.
- Make sure your gas, electricity and water supplies are on.
Understanding why a boiler not firing issue happens in winter
Cold weather puts your heating system under extra strain. Outdoor pipework freezes more easily, boilers work harder and small faults show up more quickly. In towns like Bordon, Liphook and Alton, we often see a surge of winter faults linked to frozen condensate pipes and low system pressure.
Frozen condensate pipe
This is one of the most common causes of a boiler refusing to fire in freezing weather. Condensing boilers produce waste water which travels through a plastic pipe to a drain outside. When the pipe freezes, the boiler detects a blockage and locks out for safety.
- Listen for gurgling or sloshing noises.
- Look for an external white plastic pipe—often 21.5mm in diameter.
- If safe, pour warm (not boiling) water over the pipe to thaw it.
If the pipe repeatedly freezes, consider insulation or rerouting. This is a common prevention upgrade for homes across GU35 and GU34.
Low boiler pressure
Low pressure prevents your heating system from circulating hot water correctly. Cold weather can accelerate pressure drops due to minor leaks or radiator bleeding.
You can check the pressure gauge yourself: most systems require around 1.0–1.5 bar when cold. If it’s below this, you may need to top it up using the filling loop. Instructions are usually on a sticker attached to the boiler or inside the manual.
Common UK boiler fault codes and what they mean
Modern boilers display fault codes to help pinpoint problems. Here are some of the most frequent ones homeowners see when dealing with a boiler not firing issue.
- F1 / E1 (Low pressure) – System water pressure has dropped too low.
- F28 / EA (Ignition failure) – The boiler cannot ignite, often due to gas supply problems or frozen pipes.
- F75 – Pump issue or pressure sensor fault.
- L2 – Ignition lockout, commonly caused by condensate blockages.
- E133 – Gas supply interruption, sometimes caused by regulator freeze in extreme cold.
- F22 – Dry fire/low water, often linked to pressure problems.
If your boiler keeps showing the same code even after a safe reset, it likely needs professional attention.
Winter readiness checklist for your heating system
Preparing your boiler before a cold snap helps prevent breakdowns and keeps your system running smoothly all winter. Homeowners in Bordon, Farnham and nearby villages often find that doing a little early maintenance saves a lot of stress once temperatures plunge.
- Have your boiler serviced annually by a Gas Safe engineer.
- Check your radiators heat evenly and bleed them if needed.
- Insulate external pipework, especially the condensate pipe.
- Test your heating before winter to catch issues early.
- Check for steady boiler pressure between 1.0–1.5 bar.
- Make sure vents and flues are clear of debris.
- Review your heating schedule for seasonal changes.
When to call an engineer
If the heating still won’t fire after basic checks, or if you smell gas, hear unusual noises, or see persistent error codes, contact a professional. A qualified Gas Safe engineer can diagnose deeper issues such as faulty ignition components, failed pumps or blocked heat exchangers. These require specialist tools and knowledge to fix safely.
Next steps
If your boiler still isn’t firing and you’d like professional help, you can reach us at (01420) 558993.