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How to Unfreeze a Frozen Condensate Pipe

The boiler condensate pipe is the pipe that allows water drained from your heating system to be disposed of with your household wastewater. Some households have their condensate pipe connected to their waste pipe internally, however, this isn’t always possible.

Many households have external condensate pipes that are vulnerable to freezing in the winter. A frozen boiler condensate pipe can prevent your boiler from functioning properly, leaving you without heating and hot water.

The good news is that a frozen condensate pipe is relatively easy to fix yourself, soyou don’t necessarily need to call out a heating engineer. Here we’ll share our top tips on how to unfreeze a boiler condensate pipe safely, along with advice on how to protect your condensate pipe in time for the winter.

What temperature do pipes freeze?

Condensate pipes tend to freeze when outside temperatures fall below the freezing temperature of water i.e. 0 °C. This is very common in winter in the UK.

It’s the busiest time of year for heating engineers and plumbers, as many boilers break down as a result of frozen condensate pipes.

How to spot frozen condensate pipes

You’ll soon know if you have a frozen condensate pipe as things will get rather chilly. You’re unlikely to have access to heating and hot water. There may also be some rather strange gurgling sounds coming from your boiler.

If you take a look at your boiler’s control panel, you’re likely to find it’s stopped operating. If the boiler has sensed that the condensate pipe is blocked by ice, it will turn itself off to prevent damage. It may also be displaying a fault code. This will vary depending on your boiler model. Consult the operating manual to identify it and confirm your suspicions.

A visual inspection of the boiler condensate pipe should give you a good idea of where it’s frozen. It’s most likely to be at the exit, where the water trickles out into the drain. Freezing is also common in flatter areas of the pipe or at its joints (elbows).

How to unfreeze a frozen condensate pipe

Providing you have safe access to your boiler condensate pipe, you should be able to unfreeze it with hot water.

To do this:Heat water in your kettle or microwave (make sure the water isn’t boiling as you could accidentally burn yourself or crack a frozen pipe)Transfer the water to a watering can or jug for easy pouringSlowly pour the water over the frozen section of the condensate pipePay attention to any flat surfaces or elbows where ice is more likely to form

If pouring hot water on your  frozen condensate pipe doesn’t work, you could try using a hot water bottle instead. Leave it on the frozen section for a longer period. When you see water leaving the pipe or hear a trickling sound, you’ll know that the blockage has cleared.

Once you have unfrozen your condensate pipe, you can attempt to restart your boiler. To do this, follow the instructions in your boiler’s operating manual. This should be available online if you don’t have a paper copy to hand.

If the reset is successful, the fault code on your boiler will disappear and your hot water and heating will return.

Both of these methods can also be used for unfreezing a frozen drain pipe for outdoor boiler appliances too.

How to prevent frozen condensate pipes

We all know that here in the UK, it’s common for temperatures to drop below freezing in the wintertime. There are many preventative measures you can take to protect your boiler condensate pipe from the cold, though some methods may require professional assistance.

Boiler condensate pipe insulation

One of the ways you can protect your condensate pipe from the cold is with waterproof lagging.  Condensate pipe lagging will help to keep your boiler condensate pipe warm, even in freezing temperatures.

Installing this type of insulation is something you can do yourself to save money. You can buy waterproof pipe lagging online or from all good hardware stores.

Moving the boiler condensate pipe internally

Alternatively, you could get in touch with a Gas Safe registered engineer and find out how much it would cost to move your boiler condensate pipe to an internal location. That way, you wouldn’t have to worry about the water freezing inside it in the wintertime.

Re-routing a condensate pipe is not a task you should consider doing yourself and is likely to be quite challenging. Only heating engineers registered with Gas Safe can legally handle pipes connecting to a boiler and gas supply.

Changing the angle of the condensate pipe

Increasing the fall of your boiler condensate pipe can improve the flow of water and reduce the risk of a frozen condensate pipe in colder temperatures. Again, this is something that you would need to pay a heating plumber to do on your behalf.

Increase the size of the boiler condensate pipe

Making your condensate pipe larger will improve its flow and help to prevent internal freezing. Condensate pipes are plastic and must be at least 22mm in diameter, however, increasing them to 32mm allows for thicker insulation and could make a significant difference.

Still having problems with your heating and hot water? Hometree can help

If you’ve attempted to unfreeze a frozen condensate pipe but are still having issues with your heating and hot water, there may be another problem with your boiler. Hometree’s boiler cover plans are the quick, convenient and cost-effective way to deal with any fault and avoid expensive call-out and repair fees.

Simply phone our 24/7 helpline and our team of technical experts will help you troubleshoot the problem. If it can’t be resolved over the phone, we’ll send out one of our friendly, Gas Safe registered engineers to give you a hand and provide further advice.

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