What Is A Condensate Pipe & How To Defrost It?

Has your boiler frozen over and is refusing to work? Are you unable to figure out what is wrong with it and how you can fix it? It can certainly be quite annoying when the boiler freezes and stops working right when you need it the most.

In extreme winters, this is a fairly frequent occurrence. If you reside in one of the colder regions, you might have experienced this more than once. Taking the boiler out for repair is not always be the most prudent option, especially if this happens often.

What is better is to understand why this happens, what you can do about it, and how you can keep it from repeatedly happening in the future.

In this article, we walk you through the basics of the problem, from seeing what a condensate pipe is and why it freezes to the process of thawing the frost and keeping it that way.

Condensate Pipe, What It Is & How It Works

Over the last couple of decades, the use of condensing technology in gas combination boilers has become a norm aimed at boosting their efficiency. 

Boilers based on this mechanism capture the heat present in the flue gasses and pass it through the heating system repeatedly to warm the water in the boiler. This process of extracting the heat from the fuel gasses reduces their temperature from about 130℃ to 50℃.

Such an accelerated fall in temperature leads to condensation. The resultant residue needs to be emptied out. This amount can be as much as two liters each hour for an effective boiler. 

The pipe that drains this water after use in the heating system is called the condensate pipe of the boiler. It discards this residue to be disposed of with the household wastewater.

While it is ideal for this pipe to be internally linked to the wastewater system of your house, there are times when this is not possible. In such cases, the condensate pipe is attached externally to the draining system of the house.

Such exposure of the pipe to the rough weather and conditions outside leaves it vulnerable to freezing, particularly when the temperatures are especially low or there is an extended winter.

The condensate pipes that are channeled through wall cavities or outbuildings such as garages that are not generally heated by the house heating system tend to have greater chances of frosting over.

Where It Is

The condensate pipes used in boilers are simple to find. These boilers are made out of plastic. Since these are not made out of metal, condensate pipes are easy to locate amidst the several other pipes linked to the boiler, all made of metal. 

A condensate pipe drains the residue liquids of the heating process, and thus leads outside, generally emerging out of the lower part of the wall, over a drain. Typically, the pipe is 2.2cm in diameter, if connected to the drainage system internally, and around  3.2cm if this pipe is externally drained. 

The increased width for use in external settings is meant to prevent internal freezing. However, it is not enough to totally eliminate the possibility of pipe freeze due to extreme temperatures. 

To ensure minimum exposure to the cold, the pipe, when outside, should be of a shorter length than one that is internally connected to the drainage system. It also needs to be sharply angled to keep wastewater from other sources from entering it.

Why do Condensate Pipes Freeze?

A condensate pipe that is externally connected to the drainage is clearly exposed and vulnerable to weather extremes and their effects. In case of very low temperatures or prolonged winters, this can mean that the pipe is amenable to freezing.

Such temperatures can cause the acidic water passing through the pipe to start freezing. This, in turn, blocks the pathway for more water to drain. Eventually, it can lead to the buildup of water inside the boiler, which can cause it to malfunction.

In most cases, if the condensate pipe freezes, the boiler stops working to prevent further damage to the machine. The pipe then needs to be thawed out to restore water drainage before reusing the boiler.

How do I know if my boiler condensate pipe is frozen?

Before setting out to unfreeze the condensate pipe, you need to make sure that it is indeed the reason behind the malfunctioning. One simple indicator will be a gurgling sound emanating from the buildup of water in the boiler, not finding a channel for drainage.

To make certain, however, most boilers display an error message which will tell you exactly what is wrong with it. If that is not the case with yours, think about whether it was working fine before the onset of the extreme winter. If it was, the malfunction is probably due to the pipe freeze.

How do I Thaw a Condensate Pipe?

Once you have ascertained the error is indeed due to the freezing of the condensate pipe, you can move on to rectify the error. It is reassuring to know you can do it yourself with a few easy steps without the need to call a professional.

Before applying the actual solution, you need to locate the exact part of the pipe that has frozen over. This is needed to ensure you are thawing out the right part of the pipe, especially when it has dips or bends.

1. Heat The Water

First, ready some warm to hot water in a microwave or kettle. Make sure it is not boiling as that can entail accident hazards and/or harm to the pipe.

Put this heated water into a jug or watering can for easy application on the frozen area of the pipe.

2. Pour It On The Pipe

Next, you need to pour this warm water over the part of the pipe which is frozen. When unfreezing the pipe, it is useful to first thaw the pipe’s outlet if it is partially or fully frozen. 

This will allow water in the other parts to escape once the rest of the pipe is thawed.

Apart from this, it is advised to pour hot water on any elbows or flat sections as these typically freeze faster.

3. Use A Hot Water Bottle

If the frost doesn’t thaw by pouring the hot water over it, you should go for a hot water bottle. This would keep the frozen part in contact with the heat for longer. You will know it has worked when you hear a trickling sound of the water leaving the pipe. 

4. Reset The Boiler

When you are sure the issue has been resolved, and the pipe has been properly unfrozen, you can reset the boiler to clear the error codes shown earlier. Once they are successfully cleared, the boiler would restart.

How To Prevent The Condensate Pipe Freezing In Future

It is desirable to prevent the pipe from freezing in the first place. There are ways you can do that yourself or even consult a professional to help you ensure minimum chances of frozen blockage. 

The simple, most direct solution is to increase the pipe’s insulation to provide it added shielding against the cold. The insulation has to be waterproof, or it will work quite the opposite. 

The more permanent solution would be to divert it and internally connect it to the drainage to cut out any exposure to the freezing temperatures altogether. 

Alternatively, you can increase the diameter of the pipe to 3.2cm and steepen the incline to aid easy flow of water through it, reducing chances of internal freezing. 

Last Updated on April 11, 2021

Frequently Asked Questions

Do All Frozen Pipes Burst?

All frozen pipes do not burst. Thawing the ice is, in fact, what increases the risk of pipe burst by further adding to the pressure. This is the reason pipe bursts are more common towards the end of winter as the frozen blockage begins to thaw.

Will Outdoor Pipes Freeze At 0 Degrees?

While it is possible for pipes to freeze at 0 degrees, this will take prolonged exposure to this temperature for this to happen. It would take at least six hours for a pipe to turn to ice at this temperature. Freezing is much more likely when temperatures drop as low as -10 degrees. 

What can I use to wrap the pipes from freezing?

To wrap the pipes and keep them from freezing, you can use old towels and fasten them around the external pipes with duct tape. Alternatively, for a more durable solution, you can use foam insulation for the purpose.


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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