Posted on: 19 August 2026
Thinking about replacing your boiler but wondering what actually happens on installation day?
For many homeowners, replacing a boiler isn’t something they do very often, so it’s understandable if you’re unsure what to expect. How is the old boiler removed? Will changes need to be made to your heating system? What happens once the new boiler is installed?
While every property and heating system is different, here’s a step-by-step guide to what you can generally expect when having a new boiler installed.
1. Choosing the Right Boiler for Your Home
Before installation can begin, you’ll need to determine which boiler is suitable for your property.
It’s not simply a case of choosing a particular brand or the boiler with the highest output. Factors that should be considered include:
- The size of your property
- Your existing heating system
- The number of bathrooms
- The number of people living in the property
- Your heating and hot water requirements
- The type of boiler required
- Your budget and preferences
For example, a combi boiler can be a great option for many homes, but a property with several bathrooms and high simultaneous hot water demand may benefit from a different type of system.
Getting this right at the beginning helps ensure your new boiler is suited to your household rather than simply replacing like-for-like without considering your needs.
2. Getting Your Boiler Quote
Once you have an idea of what you need, the next step is finding out your options and getting a quote.
At solv, we’ve made this part of the process easier with our online boiler quotation tool.
You’ll answer a few questions about your property and existing heating system before being shown suitable boiler and package options, giving you an indication of what a replacement could involve without having to wait for an initial appointment.
If you’re considering converting from oil to gas, you’ll need to contact our team directly so we can discuss the requirements for your property.
3. Preparing for Installation Day
Once you’ve chosen your boiler and your installation has been arranged, there’s usually very little you’ll need to do.
It’s helpful to make sure your engineer has clear access to:
- Your existing boiler
- Relevant pipework
- Heating controls
- The areas immediately surrounding the boiler
Your engineer can let you know beforehand if there are any other preparations required for your particular installation.
4. Removing Your Existing Boiler
On installation day, your engineer will safely isolate the existing heating system before disconnecting and removing the old boiler.
What happens next will depend on the type of installation.
A straightforward replacement in the same location may require fewer alterations, whereas changing the boiler type or moving its position can involve additional pipework and changes to the existing heating system.
This is one reason why every boiler installation is slightly different.
5. Preparing Your Heating System
Before connecting your new boiler, your heating system may need to be cleaned to remove debris or sludge that has accumulated over time.
Keeping the system clean is important because contaminants circulating through your heating system can potentially affect the performance of your new boiler.
The work required will depend on the condition and design of your existing system.
6. Installing Your New Boiler
Your engineer can then install the new boiler and complete the necessary connections.
Depending on the installation, this could include work to:
- Heating pipework
- Gas or oil supply
- Flue
- Condensate drainage
- Heating controls
- Other components within the system
If the new boiler is being installed somewhere different from the old one, additional work may be required.
7. Testing and Commissioning
Installing the boiler isn’t the end of the job.
Once everything is connected, the system needs to be thoroughly checked, tested and commissioned by the engineer.
This helps ensure the boiler is operating correctly, safely and efficiently before it’s handed over to you.
8. Setting Up Your Heating Controls
A new boiler is only one part of an efficient heating system. Having suitable heating controls can help you manage when and how your home is heated.
Depending on your installation, this may include a programmable room thermostat or other heating controls.
Your engineer will explain how to use your new controls so you’re comfortable adjusting your heating and hot water once the installation is complete.
9. Your Boiler Handover
Before leaving, your engineer should talk you through your new boiler and heating system.
This is your opportunity to ask questions about:
- Using your boiler
- Adjusting your heating
- Checking boiler pressure
- Using your thermostat or programmer
- What to do if an error code appears
- Ongoing maintenance
Keep any manuals and paperwork somewhere accessible – you may need them in the future.
10. Registration, Warranty and Future Servicing
Depending on the boiler and installation, there may also be registration and warranty requirements following installation.
It’s important to understand the terms of your boiler warranty, including any requirement for annual servicing.
Having your boiler serviced regularly can help maintain its efficiency and reliability while identifying potential problems before they become more significant.
Is Every Boiler Installation the Same?
No – and that’s an important point when researching a replacement boiler.
A straightforward replacement of an existing boiler can be quite different from:
- Changing boiler type
- Moving a boiler to another room
- Converting an existing heating system
- Changing from oil to gas
- Making substantial alterations to existing pipework
Your property, current heating system and what you want from your new system will all influence what’s involved.
How Long Does a Boiler Installation Take?
There’s no single answer, as the amount of work required varies.
A straightforward boiler replacement will generally involve less work than a conversion, relocation or installation requiring significant changes to the existing heating system.
Your installer should be able to give you a better idea of the expected timescale once the requirements of your installation are known.
How Can solv Help with Your Boiler Installation?
At solv, we install replacement boilers for homeowners across Northern Ireland.
Rather than taking a one-size-fits-all approach, we consider your property, existing heating system and household requirements to help identify an appropriate solution.
We install boilers from a range of leading manufacturers and offer different package options depending on your requirements.
And if you’re only at the research stage, you don’t have to arrange an appointment just to start exploring your options.
Get an Instant Boiler Quote Online
Our online quotation tool lets you answer a few questions about your home and current heating system to see suitable boiler and package options and get an indication of the cost of replacement.
If you’re looking to convert from oil to gas, contact the solv team directly and we can discuss your options.
Frequently Asked Questions
Do I need to be at home during a boiler installation?
You’ll generally need to provide access to the property, although your installer can advise you about what will be required on the day.
Will I be without heating and hot water?
Your heating and/or hot water will need to be unavailable for at least part of the installation while the existing system is isolated and the new boiler is connected. Your engineer can advise what to expect for your particular installation.
Can I move my boiler when I replace it?
Potentially, yes. However, moving a boiler can require additional pipework, flue and drainage considerations, so the proposed new location will need to be assessed.
Do I need to replace my radiators when I get a new boiler?
Not necessarily. Whether any radiators need attention will depend on their condition and the requirements of your heating system.
Can I get a boiler installation quote online?
Yes. solv’s online quotation tool allows you to provide some basic details about your property and heating system and explore suitable boiler and package options.