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6 Top Tips for buying a new boiler

If you’ve decided the time has come to get a new boiler, you might be daunted by the task ahead. After all, a boiler is a significant investment that you’ll want to last you for the next 10-15 years. But unless you’re in the heating industry yourself, there’s an overwhelming amount of jargon to navigate. From all of the anecdotes and heating myths from well-meaning friends; to all of the different makes and models of boilers; it can be hard to know where to start. But don’t worry, The Heating People are here to help! We’ve put together this handy guide to help you on your journey to your perfect new boiler.

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Buying a new boiler? If so, you might be daunted by the task ahead. After all, a boiler is a significant investment that you’ll want to last you for the next 10-15 years.

But unless you’re in the heating industry yourself, there’s an overwhelming amount of jargon to navigate.

From all of the anecdotes and heating myths from well-meaning friends; to all of the different makes and models of boilers; it can be hard to know where to start. 

But don’t worry, The Heating People are here to help! We’ve put together this handy guide to help you on your journey to your perfect new boiler.

For tailored advice, contact us today to book your free survey.

Tip 1: Find an expert installer you can trust

This is the most important tip for buying a new boiler.

In fact, we could scrap all of the other tips! Because the right installer will guide you through the whole process; and will help you to address everything else in this blog!

But doing a bit of research and thinking about some of the important considerations ahead of time; will help you to make an informed choice.

Gas Safe

First off, when looking for an engineer, it’s important to recognise the safety implications. Most heating systems in the UK are currently powered by gas.

So, it’s vital to check that your engineer is Gas Safe registered.

We’ve dedicated a whole blog to the reasons why choosing a Gas Safe engineer is so important. And you can read it here. But suffice it to say, choosing a cowboy can have fatal consequences. So don’t take the risk!

But your engineer needs to have the skills and expertise to get the best out of your boiler; as well as being qualified to install it.


There’s little point investing thousands of pounds in an all-singing-and-dancing efficient new boiler; and asking a charlatan to install it for you. You’ll just be wasting your money.

Unfortunately, there is a vast skills and knowledge gap within the heating industry. The Heating Hub says that:

‘99% of installers do not understand how condensing gas boilers work and therefore cannot set them up to run as they were designed to.’

This is a frightening statistic, but unfortunately, we’re not surprised. We’re tired of the one-size-fits-all approach to boiler installation. 

Why expertise matters when it comes to your new boiler…

An engineer installing a heat pump.A lot of heating ‘engineers’ still use the crude method of counting radiators to determine boiler size. But this is inaccurate.

It wasn’t the right way to do it in the past. And it isn’t the right way to do it now.

It’s just another illustration of the lack of understanding; and the lazy approach to heating design that plagues us in the UK.

Rest assured that you won’t find any of our engineers counting radiators. We install boilers the right way, following the industry standard (Part L of the Energy Efficiency Regulations). 

We’re proud to be part of the Heat Geek Elite (link at the end of this article). Our tailored service uses scientific calculations to match you with the perfect boiler for your home and lifestyle. 

So when looking for a new boiler; remember that it will only be as good as the engineer who sets it up!

Tip 2: Decide on the right type of boiler for your needs

A man looking at different doors.When you’re thinking about a boiler replacement, the first question to ask yourself is what type of boiler you want.

There are three main types of boiler system: heat-only or conventional boilers; system boilers; and combination or ‘combi’ boilers.

Just because you currently have a particular type of boiler now, doesn’t mean you’re stuck with it forever.

You need to start by asking yourself whether you want to replace like for like. Or whether you want to take the opportunity to switch to a different type of boiler.

Stick or switch?

A man thinking a bout a combi boiler.Switching to a different type of boiler is generally more expensive than a like-for-like swap; due to the change in infrastructure. But a boiler is a significant investment, and you’ll want to get it right.

Switching to a different type of boiler might improve your home comfort. As well as reducing your energy bills, so you need to think long term.

Having said that; if you were happy enough with your old boiler when it was working well; then the same type of boiler could be a good option.

If lots of circumstances have changed since your last boiler was installed; or you inherited it from a previous occupier, you should consider your other options.

If for example, your family has grown, and your current combi boiler is struggling to keep up with your demands for hot water; you might be better off switching to a system boiler.

So what are the options? Although there are many different makes and models of boiler, they all fall into three basic types. For the sake of this blog, we’ll keep this brief:

Heat-only or ‘conventional’ boilers

Diagram of a heat-only boiler system.Heat-only or conventional boilers are often thought of as the traditional way of heating a home.

They’re designed to provide both heating and hot-water with the use of an additional cold-water tank and hot-water cylinder.

Heat-only boilers are typically found in larger properties; as they can supply large amounts of hot water to multiple taps and showers at the same time.

These boilers have a large feed tank which is usually stored in an attic or loft. This tank fills with cold water from the mains supply. The water is heated by the boiler; and is stored in the hot water cylinder to supply your taps and shower heads.

Where do heat-only boilers work best?

Heat-only boilers work well in large households with multiple bathrooms. Because they can supply large amounts of hot water to multiple outlets at the same time.

Another bonus is that they can be fitted with an additional electrical immersion heater. This can provide you with back-up hot water in the event of a boiler breakdown.

The drawbacks of these boilers are that they need more space than the other two types of boiler; because of the external tank and cylinder.

Because they store hot water, there is a lack of instant hot water. Once you’ve used up what’s in the cylinder, you’ll have to wait for it to refill.

You can read their pros and cons here.

Combination or ‘combi’ boilers

Diagram of a combi boilerCombi boilers are the most popular type of domestic boiler sold in the UK.

‘Combi’ is short for ‘combination’ boiler. Because it combines all the components of a traditional central heating system into one compact unit.

A combi boiler provides hot water on demand; rather than storing it in a tank or cylinder. It works by taking cold water directly from the mains and heating it as and when you need it.


Where do combi boilers work best?

Combi boilers are useful in properties that are short on space because the boiler itself is the only component part. They’re often compact enough to fit inside a kitchen cupboard.

Another advantage is that they never run out of hot water because they heat it on demand. But they do struggle to supply multiple outlets at the same time.

So, if you have multiple bathrooms; or family members who want to take showers at the same time; a combi isn’t your best option.

You can read their pros and cons here.

System boilers

Diagram of a system boilerSystem boilers feature aspects of both a heat-only boiler and a combi.

Like a heat-only boiler; a system boiler needs a hot water storage cylinder to heat and store hot water for your taps. But it doesn’t need a tank in the attic because like a combi; it takes its water supply directly from the mains.

Once heated, the water is stored in a hot-water cylinder until it’s needed. Since there is a large store of hot water always available; a steady supply can be maintained even if multiple taps or showers are in use at the same time.

Where do system boilers work best?

Similarly to heat-only boilers, system boilers work well in large households with multiple bathrooms because they store hot water.

Their advantages over heat-only boilers are that they don’t require as much space; and they have a much wider range of control options available.

They’re also easy to integrate with renewable heating systems such as solar power. And they can be installed to low temperature, high efficiency heating systems.

Again, like a heat-only boiler there is a lack of instant hot water. Although this can be minimised with the correct controllers.

You can read their pros and cons here.

Tip 3: Choose the right size of boiler for your needs

The next thing to think about is what size of boiler you need.

We don’t mean the physical dimensions of the appliance itself. But rather how much energy is output by the boiler in terms of heat, which is measured in kilowatts (kW).

For example, a 25kW boiler uses 25,000 watts (25 kW) of power per hour; to heat the water for your central heating.

Generally, the more heat and hot water you require for your home, the higher the kW boiler you will need. But the type of boiler you have will affect this.

Choosing the correct size of boiler for your needs is crucial. If you choose a boiler that’s too big, you’ll be wasting energy and paying over the odds on your bills.

But if it’s too small, it might not be powerful enough to heat your home; or give you enough hot water.

How boilers are sized

As we mentioned earlier, there are lots of ‘engineers’ that will install much bigger boilers than you actually need. Because they either don’t understand how to design a heating system properly, or because, frankly, they’re lazy!

The only way to find the correct size of boiler is through a whole house heat loss calculation. These are the industry standard for sizing boilers under Part L of the Energy Efficiency Regulations.

These regulations provide guidance on the conservation of fuel and power under The Building Regulations Act 2010.

Energy Efficiency Best Practice requires a heat loss calculation to be conducted before installing a new boiler.

So you definitely need to avoid online ‘calculators’. Or anyone who just wants to count some radiators and have a guess!

To learn more about how boilers are sized, see our related blog: What size boiler do I need?

Tip 4: Choose the boiler manufacturer that best meets your needs

If you’ve done a Google search for a new boiler, you might be surprised by just how many boiler manufacturers there are. All offering their own extensive ranges of boilers, often with long and convoluted names!

Unsurprisingly then, we often get asked: ‘which manufacturer is best?’ by our customers. And unfortunately, there’s no easy answer – it really does depend!

Just as there’s no ‘one-size-fits-all’ boiler for everybody, there’s no ‘right’ boiler brand either.

Each brand (and individual model within the brand) has their own pros and cons. Which need to be weighed up for your particular needs.

How to choose a manufacturer

Don’t just pick the one that everyone else seems to be getting. Because what’s right for them, might not be right for you.

Although ATAG is a bit of a dark horse in the domestic boiler market; their engineering is outstanding. And they’re producing the most efficient boilers in Europe. So don’t write them off because they’re not a household name (yet!)

And hopefully it goes without saying, but you shouldn’t just pick a manufacturer because of how a boiler looks!

Lots of people like the new Lifestyle range from Worcester Bosch because they look stylish. But make sure that’s not the only thing you’re choosing them for!

Instead, it’s advisable to do a bit of research into what each manufacturer brings to the table for the type of boiler you’re looking for; and what you’re hoping to achieve with it.

After all, your boiler will be the hardest working appliance in your home for at least the next decade; so it needs some thought!

Tip 5: Check how efficient your new boiler is and what additional heating controls you might need or want

With gas prices soaring 250% since January, and COP26, boiler efficiency has become more important than ever.

At its simplest, an efficient boiler needs to burn the least amount of fuel to do its job.

An inefficient boiler does the opposite. It burns loads more fuel to do exactly the same job; which makes it more expensive to run, and worse for the planet.

To put this into context, an old non-condensing G-rated boiler that is 70% efficient wastes 30p in every £1 that you spend on heating.

Whereas a new A-rated boiler with 92% efficiency is only wasting 8p in every £1.

Unfortunately, the process involved in burning fuel for heat will always result in some heat loss and wasted energy. But, it’s clear to see that a more efficient boiler will save you money.

Changes to the law in 2005 and the Boiler Plus regulations; mean that all new boilers have condensing technology and are A-rated for efficiency. New combi boilers also have to have one of four additional energy saving devices fitted.

You should check out our related blog: How to choose an energy efficient boiler.

Heating controls

To optimise your energy efficiency, you need to pair your new boiler with appropriate heating controls.

According to the Energy Saving Trust; you can save £70 and 300kg of carbon dioxide a year by installing and correctly using a programmer; room thermostat; and thermostatic radiator valves.

You should also consider investing in smart controls. Smart heating controls can often connect to the internet and can be controlled remotely through a tablet or smartphone.

There are a huge variety of options available with smart controls, such as zoning, geo-fencing and intelligent learning systems.

This gives you smarter control of your heating; remote access; and the promise from manufacturers of energy savings of between 20-30%.

The Heating People will be able to advise you on the best options for your central heating system.

Tip 6: Check the guarantee that comes with your new boiler

ATAG iC boiler.All new boilers come with a guarantee from the boiler manufacturer.

This means that if you experience a genuine fault with the boiler during the ‘guarantee period’; the manufacturer will repair the boiler free of charge.

Different manufacturers offer different lengths of guarantees. And often offer extended guarantees if the boiler is installed by an accredited installer.

New boilers with The Heating People come with a guarantee of up to 14 years, for your peace of mind.

Once we have installed your new boiler, we’ll register it with the manufacturers to activate its guarantee.

But you need to have your boiler serviced annually by a Gas Safe engineer to maintain its guarantee; whichever manufacturer you choose.


We hope that you’ve found these tips helpful. For tailored advice on your new boiler, contact us today to book your free survey.

Useful links:

The Heating Hub article: Turning down your boiler flow rate

Heat Geek: Find a heat geek

The Energy Saving Trust: Heating Controls