How Do I Thaw A Frozen Condensate Pipe?

Please note, we can only give you basic advice on this page to do the job yourself. Make sure you use the right tools and protective equipment to avoid hurting yourself or damaging your home.

A condensate pipe carries condensation from a boiler to the outside drain and will often, therefore, run outside your property which will make it prone to freezing over the winter.

If your boiler stops working in a particularly cold spell, check to see if your condensate pipe has frozen before calling out an engineer. We’ve put together a quick, simple step-by-step guide to thawing out your condensate pipe, but remember if you don’t feel confident doing this, always call an expert for advice:

1. Find your condensate pipe: This will be a white or grey pipe that comes out of the wall behind your boiler and runs directly into an outside drain.

2. Locate the blockage: This usually happens where there is a bend or dip or at the open end of the pipe. If you run your hands over the pipe, you should be able to find a section that feels colder than the rest.

3. Thaw the frozen section: Pour hot water along the length of the pipe, repeating until thawed. Don’t use boiling water as this could damage or crack the pipe. If you’re using a kettle to heat the water, leave it to cool for around 15 minutes so that it’s hot rather than boiling. (You can also use a hot water bottle or microwaveable heat pack).

4. Restart your boiler: Once the frozen section has melted, reset your boiler (using your boiler manual if you’re unsure how to do this). It should now restart.

Prevention is better than cure

There are a few things you can do to stop your condensate pipe freezing again:

• Leave your heating on overnight – this will help to keep the pipe warm when temperatures are at their lowest

• Invest in some foam pipe insulation to wrap the pipe in

• Temporarily turn your thermostat up to a higher temperature setting (but watch out for hot radiators!)