New boiler installation: your complete guide

Boilers typically last between 10-15 years before they become less efficient and prone to breakdowns. If those breakdowns become more frequent, it could be time to consider new boiler installation.

In this guide, we cover all you need to know when planning for a new boiler, helping you to prepare for this project and make a well-informed decision that’s right for your home.

How to tell if you need a new boiler

There are several reasons why you might consider installing a new boiler…

Age of the boiler

The older your boiler gets, the less efficient it becomes as it struggles to heat your home effectively. A new boiler tends to be 90%+ efficient while older models can be less than 50% efficient.

Frequent repairs

If you’re experiencing frequent problems and breakdowns with your boiler, it could be time for a new boiler. Especially if the repairs have the potential to cost more than an upgrade.

Reduced reliability

It might be that your boiler is not working as it should. Some key signs include uneven heat distribution across different rooms in your home, water taking too long to heat up, or not heating enough water for your home’s needs.

Choosing the right boiler for your needs

There are typically three main types of boilers used in UK homes: combi boilers, system boilers, and conventional (regular) boilers.

Combi boilers

Combi boilers have no storage tank. There are four main types: gas, oil, LPG, and electric.

• Gas combi boilers use natural gas and are a common choice for homes connected to the gas network
• Oil combi boilers are an option for homes without an existing gas connection and use an oil storage tanker
• LPG combi boilers use liquefied petroleum gas (or LPG) and are an energy-efficient way of providing hot water
• Electric combi boilers are a lower carbon heating option, heating water by passing it over a hot element instead of burning fossil fuels

System boilers

System boilers have a hot water storage tank in an airing cupboard and are fed by the mains water supply.

They are more compact than conventional boilers as they don’t need a cold water tank, however, they are still larger than combi boilers.

One of the main drawbacks of this type of boiler is you’ll only have a limited amount of hot water depending on the size of your tank.

Regular boilers

Regular boilers have a hot water storage tank in an airing cupboard and a cold water storage tank in the loft.

However, before assuming you have a conventional boiler, check the cold water storage tank in the loft is connected.

The house may have previously upgraded to a system boiler and the tank may be disconnected but still in place in the loft.

Conventional boilers are arguably less efficient than other options and don’t always supply the best pressure for showers.

Which tradespeople can install boilers?

The professional you hire to install your new boiler will need to be appropriately qualified for the type of boiler you need fitting.

A boiler installation company will have fully qualified heating engineers and electricians. This is a real plus point if you’re replacing a gas boiler, as this must be removed (and the gas line capped) by a registered Gas Safe engineer.

• Gas boiler installers must be Gas Safe-registered
• Oil boiler installers must be registered with OFTEC
• Electric boilers must be installed by an electrician (to install the electrical supply circuit and wire it in) and a heating engineer (to plumb in the connections to your boiler)

On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.

What is involved in installing a new boiler?

Installing a new boiler involves five key steps:

• Assessment: A qualified heating engineer will assess your home’s heating needs and recommend the most suitable boiler size and type
• Out with the old: The system will be isolated and drained, disconnected from the electricity and thermostat, and the old boiler removed
• In with the new: Your installer will fit your new boiler as per the manufacturer’s instructions and in line with Building Regulations
• Test: Finally, the heating engineer will test the new boiler to make sure it’s functioning correctly
• Disposal: Normally, your installer will take your old boiler away with them, but if this is not an option, contact your local authority for safe waste collection

Do you need building regs for a new boiler?

Yes, building regulations stipulate various factors with boiler installation, including its location, ventilation requirements, and the positioning of the flue.

For oil boiler installations, building regs stipulate that this job must be done by a tradesperson registered under a Competent Person Scheme. This will ensure the safe positioning of the oil storage tank.

What’s more, new boilers should only be installed if they’re efficient. Regulations state that oil boilers should be at least 85% efficient and gas boilers should be at least 86% efficient.

What paperwork should I get with a new boiler?

A competent boiler installer will ensure your boiler installation complies with the relevant building regulations and apply for any necessary certification.

For example, following the installation of a gas boiler, the Gas Safe registered engineer will notify the local council. The council will then issue the homeowner with a Building Regulations Compliance Certificate.

On the other hand, you don’t need to register or notify about electric boilers.

How do I prepare my house for a new boiler installation?

Access is key when fitting a new boiler to an old system. Therefore clearing the area around your existing boiler in advance will help your heating engineer to start work without delay.

Your engineer will then turn off the power and shut off the water to make sure the area is safe before they begin work.

Do you need to change the pipework or get new radiators for a new boiler?

In most cases, the gas pipework is replaced when your new boiler is fitted. However, existing radiators can remain in place; you won’t necessarily need new radiators with a new boiler.

However, older radiators might impact your home’s energy efficiency and it might be worth upgrading them when you have your new boiler fitted.

Your heating engineer will be able to assess your current system and make any necessary recommendations for optimal performance.

How long does it take to fit a boiler?

In preparation for your boiler upgrade, you might be wondering how many hours it takes to fit a new boiler. After all, you want to minimise the disruption of being without heating or hot water.

The time it takes to install a new boiler depends on the scope of the project, the type of boiler, and the complexity of the job.

On average, it can take anything from one to three days to fit a new boiler.

Once your heating engineer has assessed your particular project, you should be provided with a more accurate timeframe.

New boiler installation cost

So, how much does it cost to get a new boiler fitted? It depends! Several factors will influence the cost of boiler installation, including:

• Your existing boiler system type and what you’re replacing it with
• The make and model of your new boiler
• How complex the installation is
• Whether you need new pipework or radiators
• Whether you’re moving your boiler to a new location

As a guide, expect to pay between £3,000 - £15,000 for a new boiler and installation. The following table provides ballpark averages for the cost of various boiler installs.

Our article on the cost of a new boiler provides much more detail to help you budget for this home improvement.

You’ll also find a wealth of information on the different types of boilers, average running costs, and the grants available.

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