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If you are searching for the best boiler installers UK homeowners can actually book, start with two fixed-price online companies: Heatable first, then iHeat. Both hold Which? Trusted Trader accreditation, both quote in about a minute, and both can fit as soon as the next working day on a straightforward swap.
This ranking is for a typical like-for-like gas combi replacement in England, Scotland or Wales. It is not a league table of every local Gas Safe engineer. We ranked the national installers we send people to, using quote speed, what is included in the fixed price, finance terms we have already published, brand range, and how the job is handled when the install is not a simple swap.
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Best boiler installers UK 2026: the shortlist
| Rank | Installer | Best for | From (fitted) | 0% finance |
|---|---|---|---|---|
| 1 | Heatable | First quote for most homes; longest 0% term we recommend | ~£1,895 | 12 to 48 months |
| 2 | iHeat | Viessmann, Alpha or Glow-worm; fastest next-day slot | ~£1,985 | 24 months |
| n/a | British Gas | Complex or surveyed jobs, not a first quote | Surveyed | 24 or 48 months |
Fitted prices are the entry figures already published on our Heatable and iHeat reviews. Your live quote will differ by boiler, flue and postcode. British Gas is listed for context on surveyed work, not as a conversion path.
1. Heatable: the installer we rank first
Heatable is a family-owned UK company (Heatable Ltd, company number 08804726) that has run a fixed-price online boiler install since 2017. It is FCA-regulated as a credit broker (FRN 805259), holds Which? Trusted Trader accreditation, and covers England, Scotland and Wales. It does not cover Northern Ireland.
The model is simple. You answer questions about your home, you see a fixed all-in price in about 90 seconds, and a Gas Safe engineer from Heatable’s approved network fits the boiler. Heatable says next-day install is available in most cases, typically within 24 hours of a confirmed booking. A like-for-like swap is usually a 4 to 6 hour job.
Two things put Heatable first. The 0% APR window runs up to 48 months on selected boilers, which Heatable’s own finance pages still advertise as “up to 4 years”. iHeat’s 0% window is 24 months. And the multi-lender panel is the practical difference if your credit is imperfect: applications that fail a single-lender setup are often routed to another panel lender.
Heatable also lets you save a quote and come back to it. That is useful if you want to sit the Heatable number next to an iHeat quote before you book. Headline pricing on Vaillant and Ideal installs is often competitive on this platform. Worcester is in the range, but Heatable has no manufacturer shareholder relationship, so Worcester is not always the keenest price in the market.
What you do not get: Viessmann, Alpha or Glow-worm. For those, use iHeat. Rural slots can stretch in peak winter. Complex flue runs or conversions can attract extras if the questionnaire was wrong, which is true of every fixed-price online installer.
2. iHeat: the second quote, and first if you want a rarer brand
iHeat is a trading style of Leads UK Ltd, independently owned, based in Westhoughton near Bolton, and operating since 2017. It also holds Which? Trusted Trader accreditation (iHeat states two years running) and is an approved credit broker. The quote is faster still, about 60 seconds, and next working day install is available on orders placed before 3pm.
iHeat’s brand list is the reason it sits on this page at all. Most online installers stop at the same five mainstream names. iHeat adds Viessmann, Alpha and Glow-worm, which matters if you have already shortlisted one of those on our best combi boiler UK guide. The free gas pipe upgrade is the other practical extra: an undersized supply pipe is one of the common day-of-install surprise charges elsewhere.
iHeat’s own listings currently show entry packages in the high-£1,700s to around £2,000, with a Worcester Greenstar 4000 listed at £2,449 fitted. Treat those as live shop-window prices. Your questionnaire figure is the one that counts. iHeat also publishes a typical installed range of £1,500 to £4,500 depending on boiler type, brand, property and location, which lines up with the spread on our new boiler cost guide.
The 0% term is shorter than Heatable’s. Published interest-bearing rates on iHeat have appeared at more than one figure, including a 10-year worked example at 12.9% representative APR on iHeat’s own finance FAQ, so use the APR and total repayable in your quote. Engineers are local Gas Safe subcontractors rather than iHeat employees, which iHeat states openly. That is standard in this segment. Experience can vary a little by postcode, and the network is smaller than the largest national names, which can matter in remote areas in winter.
When British Gas is the better type of installer
British Gas is not in our quote path. It is still the installer some homes should use. Fixed-price online tools are built for a like-for-like swap in the same cupboard, with a standard horizontal flue. They are weaker on older properties, boiler relocations, back-boiler replacements, and conversions from a regular or system setup to a combi.
On those jobs a surveyed quote is slower (often 1 to 3 weeks from survey to fit on the figures we have already published) and usually dearer. It is also less likely to blow up on the day. If your property is unusual, get the Heatable and iHeat numbers for a sense of the market, then book a surveyed installer for the actual work. British Gas is the familiar surveyed option. A good local Gas Safe engineer is the other.
How to choose between Heatable and iHeat
For the dedicated comparison, use Heatable vs iHeat. This page keeps the ranked shortlist.
- Most homes, or you want the longer 0% term: Heatable first. 0% up to 48 months, broader credit acceptance, Save My Quote.
- You want Viessmann, Alpha or Glow-worm, or you need a boiler tomorrow: iHeat first. Wider brand list, 60-second quote, next-day if you order by 3pm.
- Imperfect credit: Heatable’s multi-lender panel is the one to try first. Soft-search so your file is not hit at quote stage.
- Complex or older property: do not force a fixed-price online quote. Use a surveyed installer (British Gas or a local Gas Safe engineer).
- Northern Ireland or oil: neither Heatable nor iHeat is the right route. Use a local specialist.
Quote both. It takes a few minutes and the cheaper fitted price for your postcode swings by boiler and current promotional pricing. For the finance side of the same decision, see our best boiler finance deals ranking.
A cheap headline that misses the filter, the flush or warranty registration is not a cheap install. Compare what is in the price, then book the one that still looks right on your own quote.
What a good UK boiler installer should include
Whether you use Heatable, iHeat or a local engineer, the fixed or surveyed price should cover more than the box on the wall.
| Item | Why it matters |
|---|---|
| Gas Safe registered engineer | Legal requirement for gas work. Ask for the licence number. |
| System filter | Most long manufacturer warranties need one. Heatable and iHeat both include it. |
| System flush | Sludge left in old pipework is a common early failure on a new heat exchanger. |
| Flue kit | A standard horizontal flue should be in the price. Vertical or extended flues cost extra. |
| Old boiler removal | Should be included on a like-for-like swap. |
| Warranty registration | Missing the 30-day window is a frequent reason claims are refused. Both recommended installers register for you. |
| Gas Safe / Benchmark certificate | You need this for the warranty and for selling the house. |
| Workmanship guarantee | Heatable states 12 months on the installation work itself. iHeat also covers workmanship; check the term on your paperwork. |
If you are still choosing the boiler rather than the fitter, start with the best combi boiler UK shortlist, then run that model through both quote tools.
Finance, in brief
Heatable: 0% APR on selected boilers from 12 to 48 months, £0 deposit available on qualifying profiles, longer interest-bearing terms up to 10 years. Minimum loan £1,000. Heatable is the broker, not the lender.
iHeat: 0% APR on selected boilers over 24 months, optional deposit up to 50%, longer terms up to 10 years. iHeat is the broker, not the lender. Check the APR and total repayable in the quote, because published examples have used more than one rate.
Neither of us is a credit broker. The installer runs the application. Soft-search first. For the ranked comparison across providers, including E.On Next on long interest-bearing terms, use the finance deals guide.
Frequently asked questions
For a straightforward gas combi swap, we rank Heatable first and iHeat second. Both are Which? Trusted Trader accredited, both quote online at a fixed price, and both can install as soon as the next working day. Heatable wins on the 48-month 0% term and credit breadth. iHeat wins on brand range and a slightly faster quote. For a complex or older property, a surveyed installer is the better type of company, even if the headline price is higher.
They are separate companies. Heatable is Heatable Ltd. iHeat is a trading style of Leads UK Ltd. Quote both. Pick Heatable if you want 0% over a longer term or you have imperfect credit. Pick iHeat if you want Viessmann, Alpha or Glow-worm, or you need a next-day slot and can order by 3pm. Our Heatable review and iHeat review walk through the same comparison in more detail.
A typical like-for-like combi swap lands around £1,900 to £3,000 fully installed. Heatable’s published entry figure is about £1,895. iHeat’s is about £1,985. Conversions, relocations and back-boiler jobs run higher, often £2,800 to £4,500. See new boiler cost for the breakdown of unit, labour, flue and extras.
Online fixed-price installers (Heatable, iHeat) still send a local Gas Safe engineer. The difference is the quote: questionnaire and photos, not a surveyor visit. That is faster and usually cheaper on a standard swap. A local or British Gas survey is the safer route if the boiler is moving, the flue is non-standard, or you are converting system type.
Often, on a like-for-like gas swap in a well-covered postcode. iHeat offers next working day on orders before 3pm. Heatable typically installs within 24 hours of confirmed booking. Rural areas and the October to February peak can wait longer. Conversions are not next-day jobs.
The ones we recommend use Gas Safe registered engineers, include a system filter, register the manufacturer warranty, and hold Which? Trusted Trader accreditation. Heatable is also FCA-regulated as a credit broker (FRN 805259). Read recent reviews for your area, and make sure the quote matches the boiler location and flue you actually have.
No. Both cover England, Scotland and Wales. Northern Ireland customers need a local Gas Safe engineer. Neither is the specialist for oil boilers.
Prices and finance terms are indicative and taken from Heatable, iHeat and our existing reviews at the time of writing (August 2026). Always check the live quote for your exact figure before you book. We are not a credit broker, lender or installer. Heatable and iHeat handle quoting, finance and installation directly.