No Heating or Hot Water? Check This Pipe Before You Call a Plumber
It’s the scenario every homeowner in Southeast London dreads: you wake up on a frosty December morning, reach for the thermostat, and… nothing. The boiler is silent, the radiators are stone cold, and the house is freezing.
Before you panic and call for an emergency repair, take a look outside. Is it below freezing?
If so, your boiler might not actually be broken. It could simply be a frozen condensate pipe.
At Parallel Plumbing Solutions, this is one of the most common callouts we attend in Chislehurst and Bromley during the winter months. The good news? You can often fix it yourself in about 15 minutes with just a kettle and some warm water.
Here is our step-by-step guide to getting your heating back on.
What is a Condensate Pipe?
Modern condensing boilers are highly efficient, but they produce wastewater as a byproduct. This acidic water drains away through a plastic pipe (usually white or grey) that runs from your boiler, through the wall, and into a drain outside.
Because this pipe is exposed to the elements, the small amount of water inside is prone to freezing when temperatures drop. If the ice blocks the pipe, the water backs up, and your boiler’s safety sensors will shut the entire system down to prevent damage.
How to Confirm the Problem
Before you start pouring water, check these signs:
The Weather: Is it freezing outside?
The Sound: Is the boiler making a gurgling noise when it tries to fire up?
The Error Code: Look at your boiler display. Codes relating to "Ignition Failure" or "Blocked Flue" are common triggers for this issue.
The Visual Check: Go outside and inspect the plastic pipe exiting your wall. Is the end frosted over or dripping icicles?
How to Thaw a Frozen Condensate Pipe (Safely!)
If you suspect the pipe is frozen, follow these steps to thaw it safely.
⚠️ IMPORTANT: Never use boiling water directly from the kettle. Boiling water can crack the plastic pipe, causing a leak that is much harder to fix.
Step 1: Prepare Warm Water Boil your kettle, but let it stand for 10–15 minutes. You want the water to be hot, but not scalding. Alternatively, fill a jug with hot water from a working tap.
Step 2: Locate the Blockage The freeze usually happens at the most exposed point—often the open end of the pipe or at a bend (elbow).
Step 3: Pour the Water Stand over the pipe and slowly pour the warm water over the frozen section. Do this continuously for several minutes. You may hear a cracking sound or a "whoosh" as the ice plug melts and the backed-up water inside rushes out.
Step 4: Reset Your Boiler Once you are confident the pipe is clear, go back inside and press the "Reset" button on your boiler (sometimes you have to hold it for 3-5 seconds). If the blockage was the only issue, the boiler should fire up immediately.
How to Prevent it Happening Again
Insulate: Visit a local DIY store and buy some waterproof "lagging" (foam insulation) to wrap around the external pipe.
Heating Settings: During extreme cold snaps, leaving your heating on low continuously (rather than on a timer) can keep the condensate water warmer, reducing the risk of freezing.
Still No Heat?
If you have thawed the pipe and reset the boiler but it still won't start—or if you aren't confident doing this yourself—you may have a mechanical fault that requires a professional.
Parallel Plumbing Solutions is available for emergency boiler repairs throughout the holidays.
Need help? Call today on +44 (0)7867 360868 or +44 (0)7793 499179 to book a visit.