When temperatures drop, a frozen condensate pipe can easily trigger a boiler lockout. The issue is common in places like Bordon, Whitehill, Liphook and Alton, especially where pipework runs outside and is exposed to the cold. The good news is that most homeowners can safely defrost the pipe and get their heating running again.
What causes a frozen condensate pipe boiler lockout?
Your boiler continuously drains acidic condensate from the heat exchanger. If this pipe freezes, the boiler detects a blockage and shuts down to protect itself. Outdoor pipe runs, poor insulation and prolonged freezing temperatures in areas such as GU35, GU34 and GU9 make this more likely.
How to safely thaw a frozen condensate pipe
Thawing is usually simple and requires only gentle heat. Never use naked flames or boiling water.
- Locate the outdoor section of the condensate pipe – usually a small plastic pipe exiting the wall.
- Pour warm (not hot) water over the pipe, starting from the bottom and working up.
- Use a warm compress such as a hot-water bottle if water is impractical.
- Reset the boiler once you believe the pipe is clear.
Signs the pipe has thawed successfully
You should hear water trickling as the blockage clears. The boiler should reset without fault codes and begin firing normally again.
How to stop the pipe refreezing
Prevention is key, especially in exposed areas of Farnham and surrounding villages. A few simple upgrades can dramatically reduce repeat issues.
- Lag the full outdoor pipe with weatherproof insulation.
- Increase the pipe diameter to 32mm where feasible.
- Reduce external pipe runs during future upgrades.
- Keep the boiler running on low heat during extreme cold.
When to call a professional
If the pipe repeatedly freezes, the boiler won’t reset, or you’re unsure about the pipe’s condition, a Gas Safe engineer can reposition or redesign the condensate run for long-term reliability.
Need help? Call us on (01420) 558993 for fast local support.