What Type of Boiler Do I Need? Here's How to Choose

Are you considering getting a new boiler installed and wondering which type is right for you and your home?

Installing a new boiler is a major decision to make and with so many options available today, it can be understandably difficult to know which is the best option for your home.

PS we fit new boilers with gas installation nationwide. Simply answer these questions, get your fixed price and you could get it installed as quick as tomorrow.

Before making a final decision, it’s important to consider the following factors:

• Your current and future heating requirements.

• Your hot water demands.

• Size of your property.

• Types of fuel available to you.

• Your current heating system.

• Types of boilers you can have installed.

Your personal preferences may also be considered, for example, you may wish to opt for a renewable heating system and one that prioritises energy efficiency.

What are the different types of boilers?

Before considering the type of boiler you need, as well as other essential factors such as the size of your property and hot water demands, it’s important to be aware of the types of boilers to choose from.

Combination boilers

Combination or combi boilers are the most common type of boilers installed in UK homes.

They typically exist as a wall hung unit and provide both heating and hot water on demand.

They do not require a separate hot water storage tank and instead take water directly from the mains water supply and provide hot water as and when required.

For this reason, the best combi boilers are relatively small and so ideal for properties with limited space.

Conventional boilers

Conventional or regular boilers work together with a hot water storage tank and a cistern tank.

The water is heated and stored in the storage cylinder until required and is kept warm for many hours.

However, once the water runs out, you will need to wait until it’s replenished with more water and re-heated.

Conventional boilers are typically used in larger homes that have multiple bathrooms and radiators.

The additional tank requires space to house it and the cistern tank in the attic can restrict the installation location.

System boilers

System boilers are essentially an upgraded version of the conventional boiler. They take water from the mains and provide hot water to the radiators and storage tank.

Just like a combi boiler, all their parts are internalised and so they are much easier to install and service. Like conventional boilers, they are ideal heating and hot water solution for larger properties.

How to choose the right type of boiler for your home

Now you have a brief idea of the various types of boilers available, how do you know which type is best for your home?

Here are the major factors that will determine the right boiler choice for you and your home: 

Space available in your property

The amount of space free in your property will be a major factor as if you have limited space, you are unlikely to have enough room to house a system boiler, cold water tank and a separate hot water tank. In such circumstances, a combi boiler is likely going to be the best option for you.

Your existing boiler system

It usually makes more financial sense to replace your existing system with the same type of boiler.

However, there are certain circumstances when it may be appropriate to convert your boiler system e.g. if you live in an older property with a less than ideal heating system.

Still, this depends on available space, water pressure in your area and whether your existing pipework can handle the high pressures of a combi or system boiler.

Choosing the right sized boiler

After you have decided upon the type of boiler you want to install in your home, it’s important to consider the size. Selecting a boiler that is the right size is an essential part of ensuring it can keep up with your home’s hot water demands.

Hot water demands

How much hot water do you use? And is this likely to change in the future? For example, if you are thinking about expanding your family, possibly so.

In general, if you only have one bathroom, a boiler with a power output of between 24 and 30kW is advised, however, in properties with additional bathrooms, a boiler with between 30kW and 40kW is typically recommended.

However, if you have multiple bathrooms and they are likely going to be used at the same time, then a system boiler would usually be advised.

As mentioned earlier, this is a boiler that utilises a hot water storage cylinder, allowing water flow and pressure to be maintained, even with significant demands.

Property size

Another important factor is the size of your property since as well as providing hot water, the boiler’s role is also to provide heating.

That’s why it’s crucial you select a boiler that is large enough to heat your entire home adequately.

Residential boilers are provided with heat outputs ranging from 5kW, all the way up to 40 kW.

Considering underfloor heating? Read our complete guide on underfloor heating with a combi boiler. 

If you are installing a new system or regular (conventional) boiler, you should be careful not to select a boiler that is too large.

For instance, if you live in a small studio apartment, it wouldn’t make financial sense to install a system capable of providing heating for a large home, as this will simply result in a waste of energy and skyrocketing bills.

Regular and system boilers are considered “heat only” boilers, so as a rule of thumb guide, we account for:

1.5kW per every radiator in your home + 3kW for your water cylinder.

If you are opting for a combi boiler, you can calculate the required boiler size by the number of bathrooms/showers (as above), or, use our online quoting tool.

However, as a rough guide, check out the table below:

What happens if you choose the wrong size boiler? 

If you under spec your boiler...

In the case of combi boilers, selecting a combi boiler that is too small i.e. has a lower heat output than your home requires is not typically an issue. 

...why? 

The majority of combi boilers are designed to heat up to around 14 to 20 radiators. 

The issue is typically going to arise from the boiler not being able to meet your hot water demands, therefore, it’s important to ensure the combi boiler heat output matches your cold water flow rate. 

If you over spec your boiler...

If you choose a boiler that is too large for your home i.e. the heat output, then this generally isn’t an issue. 

...why? 

Newer boilers have something referred to as modulation. In basic terms, this means that the boiler reads some sensors and is able to adapt e.g. by reducing the heat output if it senses a lower demand. 

Choosing the right type of fuel

Most homes in the UK are connected to the gas and electricity grid, so it often makes installing and running a boiler that uses these fuels extremely easy.

However, in more rural locations of the UK, this isn't always the case and so oil boilers are a popular alternative in these circumstances. 

Greener alternatives are also becoming more popular, including biomass boilers and heat pumps, but these options will have an impact on the heating system you install, so it's worth bearing this in mind. 

Mains gas supply

As mentioned, the majority of UK homes are connected to the grid, in fact, the current gas infrastructure is connected to 8 in 10 homes.

Therefore, it often makes the most sense for homes to opt for a gas boiler as opposed to oil. 

Oil

Oil remains a popular fuel choice in rural locations of the UK that are not connected to the electricity or gas network.

Compared to mains gas, oil does suffer from a few disadvantages, including the fact they release more carbon, are typically non-condensing and fuel has to be stored and delivered regularly. 

Green/renewable fuels 

For some households opting for a greener alternative to gas and oil can be appealing, since it means you can reduce your carbon footprint and play your part in the carbon-neutral goals of 2050. 

Popular options include biomass boilers, which utilise renewable biomass e.g. wood waste, as well as heat pumps (ground source and air source), as well as fuel cell technology. 

Unfortunately, the major disadvantage of such systems is that they are expensive to buy and have professionally installed. They also require much more space than traditional gas and oil boilers and so for many households are not feasible. 

Future fuels 

You may not be surprised to learn that new, greener fuels are in development and plans for their rollout are underway.

This is all part of the government's plans to reduce carbon emissions and become carbon neutral by 2050. 

These alternative fuels include the likes of hydrogen, solar and electricity generated from renewable sources like wind and nuclear power generation. 

In fact, hydrogen-ready boilers are already available that are able to accept a 20% hydrogen mix. The hope is that in the coming decades' boilers capable of accepting 100% hydrogen fuel will be available. 

Which boiler is best for your home? 

Now that we've covered the basics, including how to choose the right type and correct sized boiler based on your home's hot water demands and available space, we can provide some common scenarios based on the type of property you live in. 

Here is a rough guide to the type of boiler required for your home: 

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