Boiler Cost Guide
How Much Does a New Boiler Cost in London? Prices and Installation
A new combi boiler supplied and fitted in London typically costs £1,650-£3,000 + VAT for a like-for-like replacement, and a system or regular boiler, or a combi conversion, typically £2,350-£4,150 + VAT. These are typical London ranges, not fixed prices; the installation scope sets your final quote. Browse our Boiler and Heating Guides for related advice.
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What affects the cost
New Boiler Costs and Boiler Replacement Costs in London
New boiler costs depend on the replacement scenario, so each range below applies to the type of work described with it. They are typical London ranges for a boiler supplied and fitted, shown excluding VAT, which is added at 20%. They are not a fixed price for your home: your written quote confirms the exact boiler, the work included and anything priced separately. If your home is on communal heating rather than its own gas boiler, these ranges do not apply.
Like-for-like combi replacement
Typical London range: £1,650-£3,000 + VAT. A new combi fitted in the same position as the old combi, reusing the existing route for the flue, gas, water and condensate pipes where the survey finds them suitable. The spread reflects the boiler chosen, its output and how much pipework or flue work the existing position needs.
System or regular boiler, or a combi conversion
Typical London range: £2,350-£4,150 + VAT. Replacing a system or regular boiler that works with an existing hot-water cylinder, keeping suitable existing equipment, or converting a system or regular setup to a combi. A conversion usually involves more pipework changes, which is why the range starts higher. Cylinder replacement is not part of this work.
Moving the boiler to a new position
Priced after a survey. Relocating a boiler adds new gas and water pipework, a new flue route and new condensate drainage. Because that work varies so much between homes, it is quoted once an engineer has seen the property rather than given as a range here.
What Does the Cost of a Combi Boiler Include?
The cost of a combi boiler should be separated into the appliance price and the work needed to install it in your home. A combi heats hot water on demand from the mains, with no stored hot-water cylinder, so it suits some homes better than others.
Same type or a change of type
is the quote a straight combi swap or a system conversion?
Suitability
has the installer checked hot-water demand, water pressure and flow for the model offered?
Fitted, not just supplied
does the figure include the labour and associated work, or only the boiler?
Whether a combi, system or regular boiler suits your existing system matters before price. A combi-for-combi replacement usually reuses much of the existing setup. Changing boiler type, such as removing a cylinder to fit a combi, is a larger job. A cheaper appliance price online does not show suitability or include fitting.
Before comparing combi prices, check three things:
Boiler Price and Installation: What Should the Total Cover?
A boiler price and installation quote should identify the appliance, labour, associated work, commissioning and any exclusions in one clear scope. Treat each item below as something to confirm in writing, not something to assume is included:
- The exact make and model of the boiler
- Labour for removing the old boiler and fitting the new one
- Flue and condensate pipe work, described specifically
- Heating controls, such as a room thermostat
- System preparation, such as cleaning, inhibitor and a magnetic system filter
- Removal and disposal of the old boiler
- Making good walls or boxing after the work
- Commissioning and handover
- How the installation will be notified under Building Regulations
- VAT, shown clearly
- Any work priced separately or still to be confirmed
Two handover documents serve different purposes. The Benchmark commissioning checklist records how the boiler was set up and tested by the installing engineer. The Building Regulations compliance certificate confirms the installation has been notified. Ask for both, and keep them with the boiler's manuals.
What Changes the Cost of a New Gas Boiler Installation?
The cost of a new gas boiler installation changes with the appliance specification, its position, access and the work needed on the existing system. The same boiler model can need very different installation work in two homes. A good quote separates confirmed work from items awaiting the survey.
Location, Access, Flue and Pipework
Moving the boiler or changing its flue and pipework can add work beyond a replacement in the existing position. An engineer needs to assess four things:
- Position and access: does the new boiler fit the space, and how easily can it be reached, for example in a top-floor flat with shared stairs? The quote should say whether it stays put.
- Flue route: does the existing route suit the new boiler? The quote should describe any new flue or terminal.
- Gas and heating pipework: are the pipes suitable? The quote should list any changes.
- Condensate drainage: where will the condensate pipe drain? The quote should say if it is rerouted.
Controls, System Condition and Water Treatment
Controls and system preparation should be specified for your installation after the engineer checks the existing equipment and the boiler manufacturer's requirements. Ask about each item:
- Controls: are the existing controls compatible, or is a new room or smart thermostat required or simply an optional upgrade?
- Cleaning method: what evidence about the system water supports the cleaning method proposed, whether a chemical cleanse or a powerflush?
- Inhibitor: is it included in the quote?
- Magnetic system filter: is it included, and is it required by the manufacturer?
For each, ask whether it is required, optional or awaiting the survey, and whether it is included or quoted separately. A boiler replacement does not on its own mean the system needs a powerflush.
Compare Boiler Replacement Quotes on the Same Scope
Boiler replacement quotes are comparable only when the appliance, work, exclusions and total payable are stated on the same basis. For Quote A and Quote B, mark each line as included, excluded or awaiting survey:
- Exact boiler make and model
- Installation position: same place or moved
- Flue and pipework changes
- Controls
- System preparation and water treatment
- Access arrangements
- Disposal and making good
- Commissioning and Building Regulations notification
- VAT
- Items still unresolved
- How long the quote is valid
- How changes to the work are agreed
A headline price with several unknown items cannot yet be compared fairly with a fully itemised quote. To close the gaps, ask each installer three questions: what exactly is excluded, what could change the total once work starts, and how would any change be agreed with you before it goes ahead?
Boiler repair, servicing and gas work
Request a Boiler Installation Quote in London
To get a boiler installation quote for your London home, tell us about the existing boiler and any changes you are considering. Call All Service 4 U on 020 3740 6785 to request a boiler installation quote. Our phone line is open 24 hours a day, 7 days a week, and our Gas Safe registered engineers work under business registration 648977.
Have these ready when you call:
- Your postcode
- The boiler's make and model, if you know it
- Where the boiler is now
- Photographs of the boiler, pipes and flue terminal
- Whether you have a combi or a hot-water cylinder
- Whether you want the boiler moved
020 3740 6785
Frequently Asked Questions
How much does a new boiler cost in the UK compared with London?
A UK boiler cost guide is only comparable with a London quote when both describe the same boiler and the same installation work. Prices vary with location as well as scope, so a national figure may not reflect London labour or access. The ranges on this page are typical London ranges, plus VAT, for the scenarios described above, not UK averages.
Does a 20-year-old boiler need replacing?
A boiler's age alone does not establish that it needs replacing; its safety, condition, parts availability and repair options need assessment. Our guide on whether to repair or replace your boiler sets out the evidence to look at. Repair should be considered first. If an engineer finds the boiler unsafe, follow the warning and do not use it until it has been made safe.
Which combi boiler should I avoid buying?
Avoid choosing any combi boiler before its specification and compatibility have been checked for your home. Ask the installer about your heating demand, how many taps or showers run at once, your mains water pressure and flow, the space available, compatible controls and manufacturer support. A brand name alone cannot tell you whether a particular model suits your property.
Does a new boiler always need a powerflush?
A new boiler does not automatically mean a powerflush is the right cleaning method. Ask the installer what evidence about your system water supports the proposed preparation, what the boiler manufacturer requires and where that work appears in the quote. A chemical cleanse may be enough for some systems, while others need more. Do not try to flush the system yourself.
Will skipping an annual service affect my new boiler's warranty?
Skipping a service can put a manufacturer's warranty at risk, but the terms depend on the boiler and how it was registered. Before accepting a quote, ask which manufacturer warranty terms apply, how often the boiler must be serviced and what records you need to keep. Keep every service record with the Benchmark checklist so you can show the boiler has been maintained.
How do I check that my boiler installer is Gas Safe registered?
Check the business and the engineer who attends. First, confirm the business is listed on the Gas Safe Register. Second, ask to see the engineer's current Gas Safe ID card and check the photo and name match. Third, look at the back of the card to confirm they are qualified for gas boiler work. Registration does not cover every type of gas appliance.
Still have a question or need urgent assistance? Call 020 3740 6785, tell us what has happened and we will tell you what happens next.