How Does Boiler Frost Protection Heating Work?

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Last updated: November 3, 2023

Frost protection is an innovative feature built-in to most modern boilers. Frost-protection works by heating up the boiler when the water temperature drops below a certain level. This ensures that the boiler system does not freeze over. Frost protection guarantees that your heating system works all year long and prevents frost-related damage from occurring in your boiler. Ultimately, this is a handy feature for anyone living in areas that are prone to very cold temperatures and weather conditions. When frost protection kicks in, costly damage resulting from frozen pipes is prevented and you don’t have to stress about cold weather and subsequent damage.

While some boilers are inside a kitchen or utility room, others are located in attics and garages and are more prone to frosting over when it gets cold. Since boilers are filled with water, there is always a risk that freezing might occur, and this is where the frost protection feature works. It is particularly useful in super cold climates where those blustering Winter days are all too common.

How it Works

When the water temperature in the boiler drops to a certain level (usually around 5 degrees), the system ignites and heats the water up, preventing any frost from bursting the pipes and breaking the boiler. It usually heats the water to about 10 degrees before turning it off. If the water temperature dips again, the process is repeated.

These clever systems can save you a great deal of money in the long run and ensure that your boiler operates optimally, no matter the temperature, without needing costly repairs. Those who do not have frost protection built-in to their boiler can fit a separate thermostat to their boiler or heating system.

There are several great thermostats on the market, from room devices to Smart systems. Chatting to a registered boiler professional can offer you some great intel on what thermostat will work for your specific boiler and central heating system. Additionally, they can advise you on specialised radiator valves and their anti-frost features.

If you’ve been wondering about how this feature can prolong the life of your boiler and save you money in the long run, it’s time to read on.

What is Boiler Frost Protection Heating?

A boiler’s frost protection heating ability is a nifty feature of most modern boilers. When the thermostat measures that the water temperature has dropped to 5 degrees, the system kicks in and heats up the water. Once it’s heated to 10 degrees, it switches off. It simply stops water from freezing within the boiler, rather than heating up the entire heating system.

Although most modern boilers have built-in frost protection, frost detection thermostats are also an option for systems that don’t have this feature.

Will Frost Protection Turn the Central Heating On?

People often think that first protection will kickstart the central heating system. However, this won’t happen unless you’ve set the radiator valve to its frost protection setting too. Ultimately this is a different feature and the two do not necessarily have to happen together.

When a boiler heats up the central heating system, it circulates hot water throughout the house via radiators; when frost protection kicks in, the water in the boiler alone is warmed up to ensure that freezing does not occur.

Won’t this Increase my Energy Bills?

When frost protection kicks in, your boiler ignites, and naturally, this will use some power. However, what it saves you in the long run (a potentially frozen boiler that is beyond repair) is certainly worth the small amount of energy it uses.

Added to this, if the baseline temperature is 5 degrees, it will only kick in when it gets super cold so it shouldn’t occur all the time or cost you too much in terms of energy bills. Since it only heats the water to about 10 degrees, it won’t create hot water.

What Can Happen to a Frozen Central Heating System?

A frozen central heating system can cause pretty serious damage and be expensive to repair. The energy consumption of frost protection is a fraction of what a damaged boiler can cost. This is why most standard boilers should have a frost detection system, or a separate thermostat to regulate the temperature and prevent freezing. Pipe frost protection is essential for any boiler unit.

Frozen pipes can lead to problems such as:

  • A blocked heating system
  • Burst piping
  • Extensive water damage to your home, floors, and furniture. Essentially, the room/s where your boiler or radiators are located could be damaged if piping bursts
  • Compromised water flow or a complete lack of water
  • A damaged heating exchanger and no heat emitting from your radiators
  • A broken boiler that needs to be completely replaced

Ideal Temperature Setting for a Boiler Frost Protection Thermostat

These thermostats are usually set to about 5 °C. If the water temperature drops to this level it will automatically kick start your boiler and it will heat up to about 10 °C. Once this temperature is reached and freezing has been prevented the boiler will switch off. If the temperature drops a few hours later, the boiler will kickstart again. While it won’t create hot water or fire up enough energy for a steamy shower, it will ensure that the water flows happily through the pipes.

Frost Protection for Radiators

While frost protection is a popular feature for boilers, it is also available for radiators. Some radiator valves will have a little frost icon, and when you turn the dial to this feature, the boiler will ensure that the radiator heats up if the temperature drops below 5 degrees. This is a great way to keep your home warm in freezing cold conditions and will ensure that the pipework remains in good working order.

You could, of course, set the temperature range to lower or higher, but 5 degrees is usually regarded as the best temperature for the job. The higher you set the temperature, the greater the chance that the frost protection feature will kick in and your utility bill will increase. When you keep it at 5 degrees, you won’t waste too much power. Nonetheless, it is an Temple temperature to ensure that freezing doesn’t occur.

Separate Thermometers

Although most modern boilers will have a frost protection function, there are some that don’t. Luckily, separate thermostats can be used to ensure that heat is retained and pipes don’t frost over. There are two types of thermostats, namely room thermostats and frost protection thermostats.

A room thermostat measures the temperature of the air in the particular room in which it is placed. Some of these however might have frost protection features that will turn the central heating on when the temperature drops to a certain level. In such an instance, radiators will turn on and your system will heat up.

Fros protection thermostats, on the other hand, are specifically designed to protect boiler systems. These are often in rooms that don’t have central heating systems such as attics or garages.

Bolster Insulation

Another way to ensure that frost damage does not cause problems for your boiler and pipes is to insulate them. You can easily do this with insulation tape, known as a jacket and this can be bought at the hardware store.

It shouldn’t cost more than seven pounds a meter and is an effective way to keep pipes warm. When you insulate your pipes you reduce the possibility of them freezing and as an added bonus, the water stays hot for longer.

If your home has a special storage tank for hot water, you could insulate this too. This is a clever way to ensure that hot water is retained in your heating system and that your boiler and pipework work optimally. However, this should be done in addition to a thermostat regulating the temperature.


When you opt for a frost protection system, your boiler and heating system is protected and can withstand even the coldest of weather conditions. This can save you a great deal of money in the long run, as frozen pipes can lead to expensive damages and the possible need to replace your boiler completely.

Any boiler in good working order should have this feature, and if you are unsure, then consult with a registered professional. If your boiler doesn’t have built-in frost protection, a thermostat can also do the trick. Smart thermostats are also a great idea if you want to upgrade to intelligent systems and can protect your boiler and pipes from the comfort of a app on your Smartphone.

Cold winter months can put a strain on pipes and heating systems, and frost protection is a key way to protect them. Get in touch if you want to learn about how these systems can work in your home or find out about our various frost protection products and boiler solutions.

Protect your pipework all year long and save on having to fork out costly repairs! Chat with the experts today.