Table of Contents

What Is a Combi Boiler?

There are different types of boilers, and a combi boiler is a combination boiler that offers both heating and hot water in one package.

They are normally made of stainless steel, and they have a built-in secondary heat exchanger for domestic hot water.

Combi boilers run in the winter to heat a building and provide hot water for any appliances that need it, but in the summer, they only run when hot water is needed.

Combi boilers are energy-efficient because they don’t store a lot of water, which means that you are only heating the water you actually need.

Continue reading to answer, “What is a combi boiler?”

How Does a Combi Boiler Work For Me?

Combi boilers have two separate heat exchanges in the same box.

One is designed to heat water, and the other warms radiators for your central heat.

The boiler is connected to your thermostat, and it communicates with the temperature you request.

When it needs to heat the room, it heats the water as it runs through the pipes to the radiator.

When you call for hot water, it heats water as it enters the main to go to the shower, sink, or anywhere else.

It is important to know that it isn’t able to heat the radiator and hot water at the same time.

If you call for hot water, it has a valve that will shut down the pipe to the radiator while it sends you the water.

Then it will open it up again when you finish.

You probably won’t notice a change in the heat in the room, but it is important to know that this is how it functions.

Benefits of Using a Combi Boiler

One of the primary benefits of a combi boiler is that it is much more efficient than a boiler that isn’t condensing. It is a cleaner option, and using one will reduce your carbon footprint significantly.

Older boilers operate at around 60% efficiency, while combi boilers are around 90%.

Older boilers only have two settings, which are on or off. Combi boilers allow you to separate water from heating, so you don’t have to turn everything on when you need hot water.

Most of the time, you can set different heat zones in your home, so you can choose which rooms you want to heat.

In addition, they use fewer pipes, which means that it is less complex and easier to maintain. You don’t need a water tank for hot water because the boiler heats it as it comes through the pipes.

Do You Save Money When You Use a Combi Boiler?

Whenever you switch appliances for something that is more energy-efficient, you save money on energy use. In this case, you are switching from an appliance that is 60% or 70% efficient to one that is 90% or more.

You won’t have to pay to have hot water stored in a tank hot, and you can create heating zones and use them as you need to.

If there are extra rooms in your home, you won’t have to heat them when they aren’t in use. This is beneficial if you have extra bedrooms or another space you don’t use very often.

The heating and the hot water are separate, so you don’t need to hear the entire system when you call for water. You will pay to use what you need and nothing more.

How Do You Know If Your Home Can Have a Combi Boiler?

New builds often come with combi boilers because they are compact and energy efficient. If you want to change your boiler out, you normally can.

You will save space because you won’t need a tank or a cylinder. People often place the boiler inside of a cupboard in the kitchen.

The boiler needs to mount on a weight-bearing wall. You fuel it with gas, so you need a gas supply. They can also work with LPG or oil.

You may not want to use this type of boiler if a lot of people live in your home because the water pressure will drop if multiple people ask for water at the same time.

You also may need to upgrade your radiator, so you will need to find out. However, this is easy when you call for more information about installing a combi boiler.

What Is Involved in installing a Combi Boiler?

Installing a combi boiler is fairly uncomplicated. There is less pipework than with other systems, and there is no additional tank.

You won’t need a separate pump because the water is mains pressured. It is a compact appliance, so you won’t need to have it fitted into the home, which saves time and money.

Are There Any Disadvantages to Be Aware of?

There are a few disadvantages, but for many people the efficiency and savings more than make up for it. First, you can’t call for heat and hot water at the same time.

The combi boiler gets all of its water from the mains, so it is difficult if more than one thing is calling for hot water at the same time. There is no backup tank to meet this demand.

You have a slower water rate because they draw from the mains, so it may take longer to fill a bathtub.

Finally, if there is a problem, it will take out your hot water and your central heating, which can be inconvenient.

However, it is compact, and it has excellent efficiency, which makes it more affordable. You also have fast access to hot water when you need it because it is heated on demand.


Combi heaters are a combination of a hot water heater and a radiator, and they are compact and convenient. They are energy-efficient, so you save money when you use them.

If you have a smaller home with few people living in it, they are a great option. You will reduce your carbon footprint and your energy bill, and you will free up the space you would need for a hot water tank.

Recent Posts


Share This Story, Choose Your Platform!