Every winter, a cold snap leaves people with a boiler that suddenly stops working, often with a fault code on the display and a gurgling noise. Very often the boiler itself is fine. The problem is a frozen condensate pipe.
Here is what the condensate pipe does, how to tell if it has frozen, how to thaw it safely and how to stop it happening again.
What is a condensate pipe?
Modern gas boilers are condensing boilers. They recover extra heat from the flue gases, and that process produces water, called condensate. A plastic pipe carries the condensate from the bottom of the boiler to a drain.
The Energy Saving Trust says your boiler is a condensing boiler if it has a plastic flue, a plastic pipe running from the bottom of the boiler through the wall to a drain, or if it is a gas or LPG boiler installed after 2005. So most homes in Gloucestershire with a gas boiler will have one.
When the condensate pipe runs outside, the water in it can freeze in very cold weather. Once it is blocked with ice, the condensate backs up and the boiler shuts down to protect itself.
Signs your condensate pipe has frozen
- The boiler stops working during a spell of freezing weather
- A fault code or warning light on the boiler display
- A gurgling noise coming from the boiler
- Ice visible at the end of the plastic pipe outside, or on the outside section
Worcester Bosch, for example, lists a gurgling noise and an EA fault code on its boilers with a digital display. Other makes use different codes, so check your boiler manual.
How to thaw a frozen condensate pipe
Only do this if you can reach the pipe safely from the ground. Do not climb a ladder in icy conditions, and take care on frozen paths.
- Find the plastic condensate pipe where it leaves the house. It is usually white or grey and runs into a drain or soakaway
- Look for the frozen section. It is often at the end of the pipe or at a bend, where water collects
- Pour warm water slowly along the pipe, starting at the end. Warm, not boiling. Boiling water can damage the pipe and joints and could scald you
- Keep going until the ice clears and the water runs out of the end
- Reset the boiler following the manufacturer's instructions
If the boiler will not reset, or the pipe freezes again straight away, call a heating engineer.
Preventing it happening again
A pipe that freezes once tends to freeze again. Worcester Bosch suggests insulating the external pipework. Beyond that, an engineer can look at how the pipe is run. Long external runs, narrow pipes and pipes on exposed or north-facing walls are more likely to freeze. Where it is possible, rerouting the condensate pipe to an internal drain removes the problem altogether.
If your boiler is being replaced, it is the ideal time to make sure the new condensate pipe is run with winter in mind. Gary looks at the pipework, flue and controls as part of every boiler installation and replacement.
When it is not the condensate pipe
Not every winter breakdown is a frozen pipe. If the pipe is clear and the boiler still will not run, it could be low pressure, a failed part or a fault in the controls. Our guide to why a boiler keeps losing pressure covers one of the most common issues.
Never remove the boiler casing or attempt repairs inside the boiler yourself. If you smell gas, turn off the gas at the meter if it is safe to do so, open windows, do not use electrical switches and call the National Gas Emergency Service on 0800 111 999.
Boiler still not working?
If you have tried the steps above and the boiler is still down, Gary can come out and find the cause. See boiler breakdowns and emergency repairs and heating fault finding.
He covers Tewkesbury, Stroud, Gloucester and the villages in between. There is no call-out charge. Call 07454 117678 or get in touch.