How to fix a frozen condensate pipe

One of the best places to be during the cold winter weather is tucked up at home with the heating on. We need our central heating and hot water more than ever when temperatures drop outside, so one of the worst things that could happen during winter is for a boiler to break down.

Sometimes when your boiler stops working it can result in a costly repair, particularly if a new part has to be sourced. Other times it may relate to your thermostat or another part of your central heating system. Sometimes, however, your boiler may stop working because of an outside factor, and a common reason for this in winter is the condensate pipe freezing over.

Do all boilers have condensate pipes?

All combi boilers have condensate pipes, so if your unit is a combi boiler then you definitely will have. Boiler legislation from 2005 made it a legal requirement for some flue gases to be recycled, in order to make units more energy-efficient. Doing this is better for the environment as it reduces the amount of wasted energy and harmful CO2 emissions being released into the atmosphere. But for this to work safely, a condensate pipe is necessary. That’s because when flue gases go through an exchanger to be recycled, the temperature must massively drop. This creates condensation which has to be drained away from the system, and that is carried out by the condensate pipe. 

The reason the condensate pipe is at higher risk of freezing than some others is due to:

  1. The amount of water it regularly has travelling through it, which can freeze when the weather is very cold.
  2. Condensate pipes have to be made of plastic, which makes them more at risk of freezing than a metal pipe.

How to thaw out a frozen condensate pipe

With most boiler-related issues, we’d always strongly advise calling a Gas Safe registered engineer. However, if your condensate pipe needs thawing, this is something many homeowners can do themselves, if they feel comfortable to.

If you think your condensate pipe has frozen, you can follow these instructions to defrost it and hopefully bring your boiler back to life.

  • Locate your condensate pipe by looking for a plastic pipe connected to your drainage system, usually positioned around window sill height outside your property. It will be between 22m and 32mm in diameter.
  • Warm some water in a jug or pan but ensure it isn’t too hot or boiling. Boiling water can damage your condensate pipe, but it also poses a safety risk to you should any spill on your skin.
  • Pour the water over the length of the pipe, including any elbows and flat parts. Once you’ve done this you may hear trickling water within the pipe, which is good news. This means that the water has started to flow again and the pipe is thawing.

If you don’t hear this, your pipe may need a little more persuading to thaw out. You can try placing a hot water bottle over it to see if this does the trick.

When the pipe has thawed, you can reset your boiler and it should work straight away.

Can I stop my condensate pipe from freezing over again?

If the weather remains cold or another cold snap hits, your condensate pipe is at definite risk of freezing over again and causing your boiler to stop working.

There are a couple of things you can do to try and prevent this happening - and both are simple things you can do yourself:

  • Firstly, leaving your heating on during cold weather with the thermostat down can sometimes help stop your pipes freezing over, although this won’t necessarily work for your condensate pipe. However, it can certainly help the rest of your pipes, and you only need to set your thermostat to around 13 degrees when you’re not at home or during the night.
  • Secondly, you can try insulating your condensate pipe by buying foam lagging tubes from a DIY store or online. Fit these around your condensate pipe to offer it some protection from the extreme temperatures of winter.

Boiler help in West Yorkshire

Not everyone will feel confident dealing with their condensate pipe, so if you live in Heckmondwike, Batley, Cleckheaton, Dewsbury & Mirfield then Smart Gas Plumbing & Heating are on hand to help.

As experienced, Gas Safe registered engineers, there’s not a boiler or central heating problem we haven’t dealt with and no job is too big or small.

If you’d like some advice, to ask a question or arrange a quote, just let us know. We’re always happy to hear from customers old or new.

To get in touch you can call us on 01924 734530 or 07900 417080, email us at or alternatively contact us via our website by completing our short  online contact form.

Whatever you need, our friendly and reliable team will always be happy to help.