Boiler installation quote: what a fair 2026 price looks like
A typical UK boiler installation quote in 2026 lands between £2,000 and £3,500 for a straight combi replacement, and £3,000 to £5,500 where the system type changes or the boiler moves. The number matters far less than what sits underneath it — this guide shows you exactly which lines to check.
- Combi swap, same position: £2,000–£3,500 fitted
- Conventional to combi conversion: £3,000–£5,000
- Get three quotes and compare the line items, not the totals
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Typical 2026 boiler quotes by job type
The single biggest driver of price is not the brand of boiler — it is how much the plumbing has to change. These are realistic fully fitted UK ranges.
| Job | Typical 2026 quote | Time on site |
|---|---|---|
| Combi replaced with combi, same position | £2,000 – £3,500 | 1 day |
| Combi replaced, moved to another room | £2,800 – £4,500 | 2 days |
| Conventional (tank) system converted to combi | £3,000 – £5,000 | 2 – 3 days |
| System boiler with new unvented cylinder | £3,500 – £5,500 | 2 – 3 days |
| Back boiler removal and combi installation | £3,200 – £5,000 | 2 – 3 days |
| Like-for-like conventional boiler swap | £2,200 – £3,400 | 1 – 2 days |
Prices sit toward the upper end in London and the South East and toward the lower end in the North. Our guide to finding boiler installation near you covers the regional picture in more detail.
What a proper quote contains
If a quote is a single figure on a text message, you cannot compare it and you cannot hold anyone to it. Insist on a written breakdown covering all of the following.
| Line item | Typical cost | Why it matters |
|---|---|---|
| Boiler unit (make, model, kW output) | £800 – £2,200 | Output should be justified, not copied from the old unit |
| Labour | £600 – £1,400 | Should state the expected number of days |
| Flue and any extension | £100 – £400 | Long or vertical flues cost noticeably more |
| Power flush or chemical flush | £300 – £700 | Often required to validate the warranty |
| Magnetic system filter | £120 – £250 | Frequently a warranty condition — check it is included |
| Scale reducer | £80 – £200 | Sensible in hard water areas, unnecessary in soft |
| Controls and smart thermostat | £150 – £400 | Check whether it is included or an upsell |
| Removal and disposal of old boiler and tanks | £100 – £350 | A classic silent exclusion |
| Gas Safe notification and certificate | Usually included | Should never be an optional extra |
Fixed price or estimate?
Ask which you have been given. A fixed price holds unless the scope genuinely changes. An estimate can move. If a quote is fixed, ask what specifically would trigger a variation — the honest answer is usually a small list, such as discovering asbestos or a gas supply pipe that needs upsizing.
Why the cheapest quote is often the dearest
When three quotes come back £1,200 apart for the same house, the gap is almost never pure profit. It is scope. The cheap one has typically left out the power flush, the filter, the disposal of the old cylinder, or the making good after pipework — all of which reappear as extras once the job has started and you have no leverage.
Put the three quotes side by side and mark each line item as included, excluded or unmentioned. The unmentioned ones are where the money hides. A quote that is £400 higher but includes a flush, a filter and disposal is usually the cheaper job.
Boiler sizing: the line nobody checks
An oversized boiler costs more to buy and cycles inefficiently; an undersized one will not keep up with hot water demand. Sizing should be based on the property's heat loss and the number of bathrooms, not on whatever was there before. Ask each installer what output they have specified and why. If all three propose the same output, that is a good sign. If one is markedly larger, ask them to justify it.
Warranty: what to compare
- Length — commonly two to ten years depending on brand and the installer's accreditation with that manufacturer
- Conditions — usually annual servicing, and often a system flush and filter at installation
- Workmanship warranty — separate from the manufacturer's, and should be stated in writing
- Benchmark logbook — must be completed and signed on the day, or warranty claims get difficult
An accredited installer can often register a longer manufacturer warranty at no extra cost, so it is worth asking which brands each firm is accredited for before you choose.
Payment terms and deposits
A modest deposit to cover materials is normal. A demand for half the job value before anyone arrives is not. Reasonable terms look like a small deposit on booking, the balance on completion once the system is commissioned and the benchmark logbook is filled in. Pay by a traceable method rather than cash, and never pay in full before the work is finished and tested.
Getting quotes that are actually comparable
- Give every installer the same brief: same boiler type, same position, same expectations
- Have them see the existing system rather than quoting from photographs
- Ask each for the same line items so the comparison is like for like
- Confirm the Gas Safe licence number for each firm and check it on the register
- Ask what the certificate arrangement is — see our boiler installation certificate guide
- Get all three in writing before you decide
FAQs: boiler installation quotes (UK, 2026)
How much should a boiler installation quote be in 2026?
A straight combi replacement in the same position typically quotes at 2,000 pounds to 3,500 pounds fitted. Converting a conventional tank system to a combi, or moving the boiler, usually runs from 3,000 pounds to 5,000 pounds because of the additional pipework, tank removal and making good.
What should be included in a boiler installation quote?
The boiler make, model and kW output, labour with expected days on site, the flue, a system flush, a magnetic filter, controls, removal and disposal of the old boiler and any tanks, making good, and the Gas Safe notification and certificate. Anything left unmentioned is likely to become an extra later.
Why is one boiler quote so much cheaper than the others?
Almost always because of scope rather than profit. Cheaper quotes commonly omit the power flush, the magnetic filter, disposal of the old cylinder or making good after pipework, and those costs reappear once the work has started. Compare the quotes line by line rather than on the total.
Should I pay a deposit for a new boiler?
A modest deposit to cover materials is normal practice. Being asked for half the value up front is not. Pay the balance on completion once the system has been commissioned and the benchmark logbook has been filled in, and use a traceable payment method rather than cash.
Is the quoted price fixed or can it change?
Ask explicitly. A fixed price holds unless the scope genuinely changes, whereas an estimate can move. If it is fixed, ask what would trigger a variation. Legitimate triggers are things like discovering asbestos or finding that the gas supply pipe needs upsizing, and a good installer will list them up front.
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