Last Updated on August 12, 2026
A new boiler is the most expensive plumbing job most households ever buy, and the one with the widest spread of quotes. The same swap can come back at £1,900 or £3,800. Both can be legitimate. Here is how to tell which is which.
The mistake: comparing boiler prices, not installed prices
The boiler itself is often £1,500 or less. What you are really buying is the installation: the flush, the filter, the controls, the guarantee and the person standing behind it. Two quotes with the same boiler in them are not the same quote.
What a new boiler costs in 2026
| Job | Typical installed price |
|---|---|
| Like-for-like combi swap | £2,500 to £4,000 |
| National online installers (fixed price, market floor) | from roughly £1,800 to £2,200 |
| System or heat-only to combi conversion | around £4,000, often £3,000 to £4,500 |
| Back boiler to combi | around £4,000 |
| Labour portion alone | £1,000 to £2,000 |
Budget combi installs tend to land £1,800 to £2,300, mid-range £2,300 to £3,000, premium brands £3,000 to £4,500.
What moves the price
Moving the boiler to a new location adds pipework and hours. A conversion from a hot water tank system adds a day or more of labour. A premium brand with a 10 or 12 year guarantee costs more up front and usually less over its life. A proper system flush and a magnetic filter are not padding, they protect the guarantee.
The checks
Boiler work is gas work. The installer must be Gas Safe registered, and the registration must cover boilers. Check the number on the Gas Safe website, not the logo on the van. If the quote includes an unvented cylinder, the installer needs a current G3 qualification too.
Then check the business. A 10 year guarantee is worth nothing if the firm vanishes in year two. A quick Companies House search tells you how long the company behind the quote has existed. Every firm in the Whito plumbers directory shows this where we could confirm it.
The sharp takeaway
Compare installed prices, like for like: same boiler tier, same flush, same filter, same guarantee length. Check the Gas Safe number and the company age. The cheapest quote that survives those checks is a good price, and the cheapest quote that does not is not a price at all.
Part of our plumber cost series. See also power flush cost and what a heat pump really costs after the grant.
