Why do boilers break down in cold weather?
A boiler breaking down is never great, but having it fail on you when temperatures plummet is the last thing you want. Unfortunately, winter is the time boilers are most prone to breakdowns with *January seeing the most breakdowns (15.56%) followed by the next busiest month, December (12.01%). On the bright side, some of these issues are preventable. To help you get ahead of them and keep your hot water and heating running, we’ll explore the most common reasons boilers fail in cold weather.
Common Reasons Boilers Fail in Cold Weather
If your heating doesn’t come on or you’re only getting cold water from your taps, there are a few potential reasons why.
1. Frozen Condensate Pipes
Modern condensing boilers use condensate pipes (this is usually a plastic white pipe that runs from the boiler to a drainage system or soakaway somewhere outside the home) to expel acidic water. When the weather turns cold and icy, these external pipes can freeze, causing blockages that shut your boiler down.
Signs that your condensate pipe might be frozen include:
- Gurgling noises from your boiler
- Radiators not heating up
- No hot water
- Fault codes on the boiler display
How to Fix It: Frozen condensate pipes can be thawed using warm (not boiling) water. To minimise future freezes, try insulating the pipe with foam lagging or repositioning it indoors if you can.
2. Low Boiler Pressure
During a cold snap our boilers have to work harder, putting the internal parts under increased pressure and making them more prone to breaking. This can result in the boiler pressure being lower than usual. Frozen condensate pipes limiting the flow of water to the boiler are another cause.
How to Identify:
- The pressure gauge on your boiler drops below 1 bar
- Heating takes longer to work or doesn’t come on at all
How to Fix It: Repressurise the boiler by carefully following the manufacturer’s instructions. If the pressure keeps dropping then check to see if the condensate pipe is frozen and needs thawing. Failing that, you might need to consult a professional to check for underlying leaks or faults.
3. Thermostat Issues
Some older, poorly calibrated or badly placed thermostats can misread temperatures, causing your boiler to switch off prematurely or fail to start.
What to Look For:
- Your home feels colder than the thermostat setting
- The boiler cycles on and off erratically
- No operational noise coming from the boiler
How to Fix It: Ensure your thermostat is in a location free from drafts or direct sunlight. Some smart thermostats can be prone to losing connection to the boiler from time to time, so make sure it is connected to the internet, batteries are still working and that it hasn’t lost connection to the boiler. If it has lost connection then refer to the user manual to establish it again.
4. Blocked Air Vents or Flues
Keeping the air vents and flues of your boiler free from obstruction is important both for its smooth operation and keeping you and your family safe. Obstructions don’t only lead to boiler failures, but harmful carbon monoxide buildup too.
How to Prevent It: Regularly inspect and clear any obstructions from outdoor vents and flues. Installing a flue guard can offer extra protection during extreme weather. Always have a carbon monoxide detector located close to your boiler so you are alerted should any harmful gases be detected in your home.
5. Overworked Systems
During winter, boilers work harder to maintain comfortable temperatures, especially in older systems. This strain can lead to wear and tear on components which then lead to other issues such as low pressure. However, there are some warning signs that things might be going awry before your boiler fully shuts down.
Warning Signs:
- Strange noises like banging or whistling
- Uneven heating across your home
How to Prevent It: The best way to stay ahead of any potential faulty parts is to have your boiler and heating system regularly serviced. This will help you avoid costly or untimely shut downs.
How to Prevent Boiler Breakdowns in Cold Weather
Prevention is always better than cure. Below are steps you can take to get ahead of any issues.
1. Insulate Pipes and Flues
Adding foam insulation to external pipes and checking for leaks can prevent freezing and blockages. A small investment in lagging can save you from big repair bills.
2. Regular Servicing
An annual boiler service ensures components are working efficiently and identifies potential issues before they become emergencies. Think of it as an MOT for your heating system.
3. Bleed Your Radiators
Cold spots on your radiators indicate trapped air, which reduces efficiency. Bleeding them is a simple task that can improve your heating system’s performance.
4. Upgrade Your Thermostat and Positioning
A smart thermostat not only ensures accurate readings but also allows you to control your heating remotely, maximising efficiency and comfort.
5. Know the Warning Signs
Stay vigilant for unusual noises, fluctuating pressure, or inconsistent heating. Catching these signs early can prevent small problems from escalating.
What to Do If Your Boiler Breaks Down
If your boiler stops working during winter, here’s what you can do:
- Check the Basics: Ensure your thermostat is set correctly, the power supply is on, and your gas supply hasn’t been interrupted
- Inspect for Frozen Pipes: Thaw frozen condensate pipes with warm water
- Restart the Boiler: Follow the manufacturer’s guide to safely reset the system
If these steps don’t resolve the issue, you should call a qualified heating engineer. Never attempt complex repairs yourself, as it could void warranties or compromise safety.
Stay Warm and Worry-Free This Winter
As with most things, thinking ahead is the best way to keep your boiler running faultlessly during the colder months. Being proactive and insulating pipes, scheduling regular servicing, and staying alert for signs of trouble is the best way to have peace of mind.
The colder months don’t have to spell disaster. Though if your boiler does fail at this or any other time of year, Custom Heat offers central heating repairs, boiler servicing and care plans to get you back up and running.
Source: *Boilers on the Blink. UK Boiler Breakdown Study 2019
