Need a new boiler? Here’s our boiler installation guide

If you’re thinking of replacing your boiler, there are several things to think about:

  • Boiler type
  • Cost
  • Timings
  • Finding a reliable gas engineer

Here are some useful tips to help you understand your options and get your new boiler installed without a fuss – and by someone you trust.

5 questions to answer before getting a new boiler

Start by asking yourself some key questions about your home and hot water use. This will help you understand what kind of boiler you’ll need. If you need help with any of them, a Gas Safe registered engineer should be able to help you.

  1. Do you ever need hot water in two rooms at the same time?

    You might sometimes have one person in your home doing the washing up in the kitchen and another running a bath upstairs.

  2. Does your bathroom have a pumped power shower? Or would you like to get one?

    Combi boilers aren’t recommended if you have, or want to install, a shower that has an electric pump. Need a refresher on different boiler types? Try our boiler guide

  3. Do you use your hot water differently at different times of the year?

    If you spend parts of the year away from home, or if you have family or friends visiting at certain times, it’s worth telling your boiler engineer about how your usage changes.

  4. Are you planning any home improvements?

    You might have other plans for your home, such as adding underfloor heating, converting the loft, or getting solar panels. Your engineer can help you understand which boiler is likely to work best when these changes are in place.

  5. Have you had any recent problems with your heating or hot water?

    Speak to your installer, so they can help prevent them happening again.

What happens during boiler installation?

Before coming to install a new boiler, the engineer will ask you a few questions about:

  • The location of your boiler
  • The water pressure
  • How many bathrooms and radiators your home has

If they’re coming to install a boiler that’s similar to your old one, it’s likely to be a straightforward installation and shouldn’t take more than a day.

If they’re switching your combi boiler to a system boiler, there’s extra work to be done, including installing a hot water cylinder. The engineer will be able to give you an idea of how long the job will take.

6 questions to ask your boiler engineer

Here are some handy questions to ask your engineer.

  1. How will the system get rid of condensate (water produced by the boiler)?

    It’s best if condensate is disposed of through internal pipes. If not, external pipes will need some protection against very cold weather.

  2. Will my heating system be cleaned?

    If you’ve noticed cold patches on your radiators, a delay in radiators getting warm, or funny noises coming from radiators or pipes, your system could need flushing out. The installer should give it a clean and use a chemical inhibitor to try and prevent a sludge buildup.

  3. Will I need scale reducers or system filters?

    If you’re in a hard water area, you might benefit from a scale reducer/system filter to prevent limescale building up. These days, it should come as standard, priced between £75 and £120¹, and included in your bill.

  4. Where will the plume be released?

    Waste gases from your boiler are released through the flue pipe into the air outside. These are known as the ‘plume’. If you’re worried that these gases are being let out too close to a neighbouring property and may cause an issue, you can ask your engineer to look into getting a plume management kit.

  5. Will the radiators need to be replaced?

    Not necessarily. Tell your boiler engineer if you’ve had issues with them and they can give you an opinion on whether you should replace them.

  6. Which energy-efficient features can I choose?

    It’s a legal requirement to have at least one of the following energy-saving features in place when you install a new boiler:

    - Smart thermostat – this lets you control your heating when you’re out and about, helping you save energy.

    - Load-compensating thermostat – this keeps a close eye on the temperature, helping your boiler to keep your home at the correct temperature.

    - Weather-compensating thermostat – this one monitors the temperature outside your home, controlling your boiler efficiently. It also takes weather changes into account.

    - Flue gas heat recovery – this system saves energy by using heat in the released gases to warm up the cold water as it goes into the boiler.

How long will it take for my boiler to be installed?

Switching to the same boiler type: it should be installed and ready to go within a day.

Switching to a different kind of boiler: if it requires a water tank and more pipes, it’ll probably take 1 to 2 days.

Changing where your boiler is located: you’ll need more pipework to fit it in its new place, and it’ll likely take 1 to 2 days.

Do I need any paperwork for my boiler?

Yes, ask your boiler engineer for:

  • a Buildings Regulations certificate showing your local authority is aware of the installation (find out more at Gas Safe)
  • a benchmark checklist showing the boiler has been fitted properly, which you’ll need for your warranty in case of any issues.

What happens next?

The installer should perform some safety checks and record the results in the boiler instruction manual.

Check that your engineer has registered your boiler installation with the manufacturer, this will be your warranty starting date.

If you have any concerns about your new boiler, get back in touch with your engineer. They’ll be able to help.

For extra peace of mind, you could get your boiler insured, giving you access to our helpline and a trusted network of Gas Safe registered engineers.

How much does it cost to install a boiler?

Switching to the same boiler type: prices start at around £1,695.²

Switching to the same boiler type, but moving its location: starting prices are the same as above, but there could be an extra £300 to £800 to pay.³

Switching to a different kind of boiler: between £2,500 and £4,500.⁴

4 tips for a more efficient boiler

Want to reduce your carbon footprint and your bills? Here are 4 boiler-efficient tips to help:

  1. Check your boiler pressure

    Your boiler pressure should ideally be between 1 and 1.5 bar. Check the pressure gauge and read our guide on repressurising your boiler.

  2. Bleed your radiators

    Air can get trapped in radiators and stop them heating up properly. Learn how to bleed them in our guide to bleeding radiators.

  3. Add thermostatic valves

    Thermostatic radiator valves (TRVs) let you choose how hot you want each radiator to get. They help you conserve energy and money in the rooms where you don’t need lots of heat.

  4. Install a smart thermostat

    With a smart thermostat, you can monitor how much energy you’re using and control your heating, all from your phone. It’s a great way to keep on top of what you’re spending and save some energy. Read more about smart thermostats from our friends at OVO.

Finding a good boiler engineer

You’re in good hands when you choose us to install your new boiler.

  • Safety is our top priority: all of our expert engineers are Gas Safe registered
  • We fit trusted brands (such as Vaillant, Ideal, Worcester Bosch), and all boilers come with a minimum warranty of 5 years
  • We’ll fix any installation problems with your heating and controls for free for the first year

Find out more.

Need a repair? Try Home Recover from OVO

If you’ve got a problem with your boiler, heating, electrics or plumbing, and you need an urgent repair, Home Recover from our friends at OVO could be just right for you. They can fix your fault for free if you’re an OVO customer, or for £79 if you’re not, when you take out Home Recover⁵, giving you all the benefits of their ultimate home emergency cover. Got a fault? Find out more.

Sources and references:




⁵ Exclusions, eligibility criteria, cancellation fees, and terms apply.

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