BOXT and British Gas are two well-known routes to a new boiler in the UK. Both aim to take you from “old boiler” to “working new boiler” without you having to coordinate multiple trades.
The real differences tend to sit in how the quote is produced, how the job is scoped, and how warranty/servicing is handled after installation.
The core difference in approach
BOXT is designed as an online-first purchase journey: you answer questions about your home, choose a package, book an install date, and BOXT says its engineers check the job against your responses before installation.
BOXT also states delivery is usually on the morning of installation, with the installer arriving in a stated early time window.
British Gas offers online journeys too, but it also clearly positions home visits as part of the quoting process for some installs (for example, its system boiler page states you book a home visit and it will quote for what you need, including moving the boiler and pipework). 
In practice, this often comes down to preference:
- If you want a fast online journey, BOXT’s model is built around that.
- If you want an in-person assessment for a tailored scope (especially where a job may be more involved), British Gas leans into that on certain boiler types.
Quoting: what “fixed price” really depends on
With any installer, the accuracy of a quote depends on how well the job is understood up front.
With BOXT, the quote is driven by the information you provide online, and BOXT states its engineers check each job against your responses to “avoid surprises on your installation day.” 
With British Gas, the quote route can include a home visit (again, particularly emphasised for system boilers), which may help identify practical constraints such as boiler relocation and pipework changes before you commit. 
Where bullet points help: when comparing quotes, don’t just compare price-compare what the quote includes.
Ask both providers to confirm the following in writing:
- the exact boiler model and controls included
- what’s included for flue/condensate routing
- what system preparation/cleaning is included (if any)
- what happens if additional work is needed on the day
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Warranty and servicing: the bit most homeowners overlook
Warranties are often a blend of:
1. the boiler manufacturer’s warranty (varies by model), and
2. the installer’s workmanship/installation cover (covers installation-related issues).
BOXT states it includes a 12-month workmanship guarantee for faults directly related to installation work (for example pipework or connections), and notes that if the issue isn’t due to installation work it may instead fall under the manufacturer’s warranty. 
British Gas states that an annual boiler service is needed to keep your warranty valid, and also notes that boiler warranties can vary depending on the model. 
A useful way to keep this simple is to ask one question of each provider: “What exactly do I need to do every year to keep the warranty valid, and who is allowed to do it?” British Gas is explicit that a yearly service is required to maintain warranty validity. 
Finance: compare the total cost, not the monthly price
Both BOXT and British Gas promote ways to spread the cost.
- BOXT states it is authorised and regulated by the Financial Conduct Authority, acts as a credit broker and not a lender, and names finance providers it works with.
- British Gas includes representative finance examples on its new boiler page (including APR/term/total payable) and repeats the servicing requirement for warranty validity.
Quick bullet checklist before choosing finance:
- APR and total payable over the full term
- deposit required (if any)
- early settlement terms
- whether finance approval affects installation timing
Which should you choose?
If your priority is an online-first buying journey with stated steps (questions → choose package → engineer check → delivery/install day), BOXT is structured around that flow. 
If your priority is an in-person assessment for a tailored quote – especially if you think you may need boiler relocation or more pipework changes – British Gas explicitly offers a home-visit route for system boiler installs.
The fairest way to compare BOXT vs British Gas quotes
Before you decide, try to get both sides to answer these six questions (it prevents most “surprises” later):
- What exactly is included in the installation scope?
- What is covered by workmanship/installation cover vs manufacturer warranty?
- What servicing is required to keep the warranty valid?
- If extra work is needed, how is it agreed and priced?
- What documentation will you receive after install (warranty info, safety certificate, etc.)?
- If you’re using finance, what is the total payable and APR?
If you tell me your current boiler type (combi/system/regular), whether you’re moving it, and roughly how old your property is, I can lightly tailor this post to a “what matters most for your situation” version-still neutral, and without inventing prices.
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