Fixed-Price Online Boiler Deals: Are They Worth It?

What is a fixed-price online boiler deal?

A fixed-price boiler deal is a boiler supplied and installed for one guaranteed price, quoted by a website rather than by an engineer standing in your kitchen. You answer a questionnaire about your home: boiler type and location, number of bedrooms and bathrooms, where the flue exits, where the gas meter is and so on. Some firms ask for photos of the boiler, flue and meter. The tool then recommends a few boiler models and shows a fixed installed price for each.

The best-known UK companies working this way are BOXT, Heatable and iHeat. Each has its own brand line-up, guarantee lengths and survey process, which change over time, so treat their websites as the source for current details. What they share is the model: a standard installation package priced upfront, fitted by Gas Safe registered engineers, often within a day or two of ordering.

These deals sit in the same price band as the fitted ranges in our new boiler cost guide: roughly £1,800 to £3,200 for a mid-range combi swap, with budget models below and premium models with 10 to 12 year guarantees above. The appeal is certainty and speed rather than a dramatically lower number.

Online boiler deals vs local installer quotes: the comparison table

Online deals win on price certainty and speed; local quotes win on flexibility and complex jobs. The table compares the two routes on the criteria that decide most people's choice. "Local installer" means a sole trader or small firm who visits before quoting.

Neither column is "better". The right choice depends on your home and on how much you value speed, certainty and a personal relationship with the installer. The sections below take each criterion in turn.

Are boiler deals online cheaper than a local quote?

For a like-for-like combi swap, online fixed prices and good local quotes overlap heavily. Online firms buy boilers in volume and run efficient scheduling, which keeps their costs down, but they also include more as standard and carry marketing and call-centre overheads. A competent sole trader with low overheads can often match or beat them on a simple swap, particularly outside London and the South East.

Where the online price tends to look better:

• Premium boilers with long guarantees. Volume buying and manufacturer partnerships mean a 10 or 12 year guarantee on a premium model is often included at a price a small installer struggles to match.
• Fully specified packages. When you add a filter, smart thermostat and cleanse to a bare local quote, the gap often closes or reverses.
• Winter. Local installers are busiest from October to February and price accordingly; online firms hold prices steadier.

Where the local quote tends to look better:

• Budget boilers on a simple swap, where the installer's margin is the only variable.
• Anything non-standard, because online firms either exclude it or price the uncertainty into an add-on.
• Bundled work, such as new radiators or a bathroom pipe run, where one local visit does everything.

The honest summary: cheap boiler deals online are rarely dramatically cheaper than a good local quote, but they are rarely dearer either, and the price is known before anyone sets foot in your house. Use the installed ranges in combi and system boiler costs as a sanity check on both.

How reliable is the online survey?

Reliable for a standard swap when you answer accurately and upload photos; the gaps are gas pipe size, flue position, drains and system condition. This is the criterion that worries people most, and rightly: an engineer standing in front of your boiler can see the gas pipe size, the flue route and the condensate drain. A questionnaire relies on you.

In practice the big online firms have refined their questions over many thousands of installations, and the photo upload step catches most problems. The items that still trip up remote surveys are:

1. Gas pipe size. Older 15mm runs cannot feed most modern combis and need upgrading to 22mm, typically £150 to £400.
2. Flue position. Building Regulations and manufacturer instructions set minimum clearances for a boiler flue terminal from windows, doors, boundaries and other openings. If the old terminal no longer complies, the new flue has to move, which may mean a longer run, a plume kit or a vertical flue. The rules on boiler flue regulations explain the distances involved.
3. Condensate drain. A boiler that drained into a sink waste is fine; one with a long, uninsulated external pipe may need rerouting.
4. System condition. A sludged system needs a powerflush (£300 to £800) rather than the chemical cleanse included in most packages.
5. Controls. Boiler Plus rules in England require a time and temperature control plus an energy-saving measure with a new combi; packages usually cover this, but check.

Reputable online firms quote any of these as an extra before work starts and allow you to cancel without charge if you do not accept. Ask how that process works before you pay a deposit. Our guide to boiler installation labour, parts and extras gives the typical price for each item so you can tell a fair add-on from an inflated one.

What do the main fixed-price companies offer?

All three sell a boiler-plus-installation package at a price fixed online, fitted by Gas Safe registered engineers; they differ in brand line-up, inclusions and guarantee terms. The points below are the kind each company publishes about itself; ranges, terms and coverage areas change, so confirm on their sites before relying on them.

National energy suppliers and large heating firms also sell boilers at fixed or near-fixed prices, usually after a home survey rather than an instant online quote. They tend to be dearer than the online specialists but offer a familiar name and in-house engineers.

None of these companies invents a new way of fitting a boiler. The engineer who arrives is a Gas Safe registered professional following the same regulations as anyone else, and the boiler carries the same manufacturer guarantee. What you are buying is a different purchasing process. Our checklist on gas safe registration tells you how to verify the engineer whoever sends them.

What is in a boiler package, and what is not?

A package normally means the boiler, flue, filter, basic controls, system cleanse, disposal and commissioning; powerflushes, flue changes and pipework are usually extra. The word "package" still hides a lot: two deals that both say "boiler and installation" can differ by several hundred pounds in what they actually include. Before comparing boiler packages, check each of these against the inclusions list.

The combi boiler packages that look cheapest at first glance are often the ones with the shortest inclusion lists. A good local quote should itemise exactly the same lines so you can lay the two side by side. The piece on how to get and compare boiler quotes shows what a complete quote looks like.

Which boilers are in the deals, and does the choice matter?

Online installers offer a curated range rather than the whole market, typically budget, mid-range and premium options from four to six manufacturers. That suits most households, who want a reliable 24 to 35kW combi from a well-known brand with a long guarantee, and it keeps the firm's engineers familiar with what they fit.

The limitation bites if you want a specific model or a less common brand. A local installer accredited with that manufacturer may be the only route, and accreditation often comes with a longer guarantee too. The comparison of the best combi boilers shows which models suit which homes, so you can see whether what the deal offers is a good match before you book.

Sizing is worth a separate check. Online tools size by bedrooms, bathrooms and radiators, which gets most homes right. If you have unusually high hot water demand, a very large or very small house, or poor mains pressure, confirm the recommended output against an independent sizing guide before accepting it.

Which should you choose? A decision list

Use the list below to decide quickly. If most of the first group applies to you, an online fixed price is a strong option; if most of the second group does, start with local quotes.

An online fixed-price deal suits you if:

• your new boiler is replacing a combi (or a system boiler keeping its cylinder) in the same position;
• the flue exits through an outside wall and nothing has been built near it since;
• you want the job done in the next few days, especially in winter;
• you want a premium boiler with a 10 year or longer guarantee at a known price;
• you prefer to arrange everything online and are happy with call-centre aftercare;
• you have no radiators, pipework or cylinder work to bundle in.

A local installer suits you if:

• the boiler is moving, or you are converting from a regular or system boiler to a combi, or removing a back boiler;
• the flue needs a vertical run, a long route or a plume kit;
• you want new radiators, a bathroom pipe run or other plumbing done at the same time;
• you value knowing the engineer who will return for the annual service and any problems;
• you want a specific model or a brand the online firms do not list;
• your home is unusual: very large, listed, a flat with a shared flue, or on LPG.

Whichever route you take:

• get at least one quote from the other route as a benchmark;
• read the inclusions list line by line and ask about the add-on process;
• check the Gas Safe ID card on the day, whoever sent the engineer;
• make sure you receive the Benchmark checklist, the guarantee registration and the Building Regulations compliance certificate.

For a fuller look at every tactic for paying less, including timing and brand choice, see the cheapest way to get a new boiler.

Are seasonal boiler offers and clearance sales worth chasing?

Sometimes, but the saving is usually modest and only real if the base price was competitive. New boiler offers cluster around Black Friday, the January sales and the quiet spring and summer months, when installers want to fill their diaries. Promotions are usually a fixed amount off selected models or a free extra such as a smart thermostat or an extended guarantee. Get a quote during the promotion and compare the final installed total with a local quote taken the same week.

A combi boiler sale at a merchant or online retailer is a different thing: a supply-only price, often on a discontinued model. It can be a bargain if you already have an installer willing to fit a customer-supplied boiler at an agreed labour rate, and you have checked with the manufacturer what guarantee you will receive. For most people the extended guarantee that comes with an installer-supplied boiler outweighs the saving on the box.

Finally, the best boiler deals are not always the ones labelled as deals. A clear, itemised fixed price for a well-sized boiler with a long guarantee, fitted promptly by a registered engineer, is the deal most households actually need.

Frequently asked questions

Are online boiler deals really fixed, or can the price change on the day?

The price is fixed as long as your answers to the survey were accurate. If the engineer arrives and finds something you could not have known, such as a 15mm gas pipe that needs upgrading or a flue that no longer meets clearance rules, most firms will quote the extra before starting and let you cancel. Where you misdescribed something obvious, the fixed price is unlikely to hold.

What is usually included in a fixed-price boiler package?

A typical package covers the boiler, a standard horizontal flue, a magnetic filter, basic controls or a smart thermostat, a chemical system cleanse, removal and disposal of the old boiler, labour, commissioning, the Building Regulations notification and guarantee registration. Powerflushes, vertical flues, gas pipe upgrades, condensate pumps and radiator work are usually separate add-ons, so read the inclusions list before comparing prices.

Which boiler offers are available on Black Friday or in the January sales?

Online installers and some manufacturers run seasonal promotions, usually a fixed amount off selected models or a free extra such as a smart thermostat. The offers change every year and are not published far in advance, so the only reliable approach is to get a quote during the promotion and compare the final installed price with a local quote. A headline discount on an inflated base price is not a saving.

Is a combi boiler clearance sale from a merchant a good way to save?

Clearance and end-of-line sales at merchants and online retailers are supply-only prices for discontinued or superseded models. The saving can be real, but you then need an installer willing to fit a customer-supplied boiler, the manufacturer may only give the standard guarantee rather than the extended one, and spares for a discontinued model can be harder to source later. For most people the fitted price matters more.

Do fixed-price installers use Gas Safe registered engineers?

Yes. The law requires anyone working on a gas boiler in Great Britain to be on the Gas Safe Register, and that applies equally to the employed or subcontracted engineers that online firms send. You should still ask to see the Gas Safe ID card on the day and check the licence number on the register, exactly as you would with a local installer.

Can I get an online boiler quote if my boiler is in the loft or needs moving?

Usually only for a like-for-like swap in the same position. Most online tools can price a loft boiler staying in the loft, but relocations, conversions from a regular or system boiler, back boilers and unusual flue runs tend to be excluded or passed to a surveyor. In those cases a local installer visit is normally the quicker route to an accurate price.

Sources and further reading

• BOXT - Fixed-price boiler installation
• Heatable - Online boiler quotes
• iHeat - Fixed-price new boilers
• Gas Safe Register - Check an engineer
• GOV.UK - Boiler Plus standards for heating in England
• Energy Saving Trust - Boilers
• Which? - Boilers (reference only)

Prices and scheme details were checked on 22 October 2026 and are shown as typical ranges. Always get written quotes from Gas Safe registered installers.