Combi boiler supplied and fitted: what that price actually includes

Supplied and fitted sounds like a complete answer. In practice it is the least standardised phrase in the trade. One installer means the boiler, the flue, a full system clean, a filter, new controls and all the paperwork. Another means the boiler on the wall and not much else, with the rest appearing as extras once the job has started.

We do not publish prices on this site, because a number on a page cannot know your house. What we can do is show you exactly what a proper supplied-and-fitted package contains, so when two quotes land on your kitchen table you can see whether they describe the same job. Around Northampton and Milton Keynes we see the same pattern weekly: the cheapest quote is usually the shortest one, and the gap closes fast once you list what each actually includes.

What should always be in the package

A complete supplied-and-fitted combi quote covers all of the following. If any line is missing, it is not necessarily a bad quote, but you need to know whether it is excluded or just unwritten.

• The boiler itself, named by make, model and output in kW. Combi 30 fitted is not a specification.
• A new flue and terminal. The old flue almost never carries over, and the quote should say whether yours is a simple horizontal run or something longer.
• Removal and disposal of the old boiler.
• A system clean. At minimum a chemical flush with inhibitor added afterwards; a power flush on an older, sludgy system. The quote should say which.
• A magnetic system filter. Most manufacturers expect one for the full warranty term.
• Controls. Since Boiler Plus, a new combi in England must be fitted with an additional energy-saving measure, usually a smart or load-compensating thermostat. If no control is mentioned, the installation is not compliant.
• Commissioning, the completed Benchmark record, and notification to Building Control through Gas Safe, which produces the compliance certificate you will need when you sell the house.
• Warranty registration with the manufacturer within the deadline, which is typically 30 days.
• VAT, stated plainly. A quote from a non-VAT-registered installer looks 20% cheaper for the same work.

Source: Gas Safe Register; Building Regulations Approved Document L (Boiler Plus)

What is often left out, and why it matters

These are the lines that turn a cheap headline into an ordinary final bill. None of them are tricks; they are real work. The problem is only when they surface after you have accepted a quote that ignored them.

• A gas supply pipe upgrade. Many older houses have a 15mm gas run and a modern combi wants 22mm. An installer who has measured yours will price it; one quoting from a photo cannot.
• Condensate pipework. If there is no drain nearby, running one is extra work, and it should be run somewhere it will not freeze.
• Making good. Cutting a new flue hole and removing old pipework leaves marks. Most quotes exclude plastering and decorating, which is fine, as long as you know.
• Scaffolding or access equipment if the flue exits high on a gable wall.
• Moving the boiler to a different room. That is a different job, not a variation.
• Thermostatic radiator valves. Often worth doing while the system is drained, rarely included by default.

Why fitted prices vary so much between installers

Set aside the house for a moment; the installers themselves differ in three honest ways. The boiler brand and warranty length they quote, because a 12-year premium machine and a 5-year budget one are genuinely different products. Their accreditations, because manufacturer-accredited installers can often register longer warranties on the same boiler. And how much of the list above they include as standard rather than as extras.

That is why comparing headline numbers tells you almost nothing. Two quotes a few hundred pounds apart can describe the same job with different boilers, or different jobs with the same boiler.

How to make quotes comparable

Ask every installer for the same itemised list in writing: boiler make, model, output and warranty; flue work; the type of system clean; filter; controls; gas pipe check; what is excluded. Any competent installer produces this without complaint, and the exercise takes each of them five minutes.

Then read the exclusions before the price. The quote that lists its exclusions honestly is usually the one written by the person who looked hardest at your house.

The short version

Supplied and fitted has no fixed meaning, so make each installer define it. A complete package covers the boiler, flue, system clean, filter, compliant controls, disposal, commissioning, certification and warranty registration. The commonest surprises are the gas pipe, the condensate run and making good.

If you want this done without chasing three firms yourself, we arrange quotes from local Gas Safe registered installers who price from the full list above, so the numbers you compare describe the same job.