When temperatures drop below freezing, one of the most common boiler faults we get called out to is a frozen condensate pipe. The good news is that it’s usually easy to fix yourself — and here’s how.
What Is a Condensate Pipe?
All modern condensing boilers produce a small amount of acidic water (condensate) as a by-product of the heating process. This water is carried away from the boiler through a narrow plastic pipe — usually running outside your property to a drain.
Because this pipe runs outside and is often exposed, it’s vulnerable to freezing in cold weather. When it freezes, the water can’t drain away and your boiler will lock out as a safety measure — usually showing an error code on the display.
How to Spot a Frozen Condensate Pipe
- Your boiler has stopped working and is showing a fault or error code
- You may hear a gurgling noise coming from the boiler
- The outside temperature is below zero or has been overnight
- You can see ice or frost on the condensate pipe outside
How to Safely Thaw the Pipe
Important: Never use boiling water directly on the pipe. Warm water is all you need.
- Locate the condensate pipe. It’s usually a white or grey plastic pipe (about 22mm wide) running from the boiler to an outside drain. Follow it from where it exits the wall.
- Find the frozen section. This is typically at the most exposed part — where the pipe exits the wall, at bends or elbows, or at the end near the drain.
- Pour warm water over the frozen area. Use a jug or watering can with warm (not boiling) water. You may need to repeat this several times. A hot water bottle held against the pipe also works well.
- Reset your boiler. Once the ice has thawed and water is flowing freely, reset your boiler following the manufacturer’s instructions — usually by pressing and holding the reset button.
What Does a Frozen Condensate Pipe Look Like?
Watch the video below to see a frozen condensate pipe and how to identify the problem on your property.
Preventing It from Happening Again
If your condensate pipe keeps freezing, there are a few things we can do to help:
- Insulate the pipe — foam pipe lagging on the external section can make a real difference
- Reroute the pipe — in some cases, we can reroute the condensate to an internal soil stack instead
- Increase the pipe diameter — a wider pipe is less likely to freeze
When to Call an Engineer
If you’ve thawed the pipe and your boiler still won’t fire up, or if you’re not comfortable working on it yourself, give us a call. Our Gas Safe registered engineers are available for call outs across Wigan and the North West.
Call us on 01257 421660 or request a booking online.
