When temperatures drop below freezing, one fault comes up more than any other: a condensing boiler that suddenly stops working because its condensate pipe has frozen. The good news is that you can often fix it yourself in a few minutes, without touching the boiler.
What is a condensate pipe?
Modern condensing boilers produce acidic water as part of normal operation. This drains away through a plastic pipe, usually white or grey, that often runs through an outside wall to a drain. If the outside section freezes, the water backs up and the boiler shuts down to protect itself.
Signs your condensate pipe is frozen
It is below freezing outside and the boiler has stopped working.
The boiler display shows a fault or lockout code. Codes vary by make, so check your manual.
You can hear gurgling from the boiler or the pipe.
The outside section of the pipe is frozen or has ice at the open end.
How to thaw a frozen condensate pipe
Find the plastic pipe where it leaves the boiler and follow it outside. The frozen section is usually at the lowest point, a bend or the open end.
Pour warm water over the pipe, or hold a hot water bottle or heat pack against it. Use warm water, not boiling: boiling water can crack the pipe.
Keep going until the ice clears and the water can drain.
Reset the boiler using the reset button or the method in your manual.
Take care in icy weather. Water poured outside can freeze quickly and leave a slip hazard on paths. Do not climb a ladder to reach a high pipe; call an engineer instead.
How to stop it freezing again
Lagging the outside section of the pipe helps, and a wider external pipe is less likely to freeze. A heating engineer can also check the pipe has a proper fall and is not routed in a way that lets water sit in it. If your pipe freezes every winter, it is worth having it rerouted or upgraded.
When to call for help
If the boiler still will not start after the pipe has thawed and you have reset it, or if the pipe is out of reach, the boiler needs an engineer. Our engineers are available 24 hours a day, 7 days a week for emergency boiler repairs in Norwich. Call 07715 998479.
