How to find a boiler installer you can trust

Check they are on the Gas Safe Register, get three written quotes, and ask each one what is excluded. Those three steps remove most of the risk, and the second one is where people usually cut the corner.

Check the register yourself, properly

It is illegal to work on a gas appliance in the UK without being Gas Safe registered. Anyone can print a card, so check the number rather than the logo.

You can search by name, business or registration number on the Gas Safe Register website. When the engineer arrives, ask to see the ID card: it has a photo, a licence number, an expiry date, and on the back a list of exactly which types of gas work they are qualified for. Someone qualified for cookers is not necessarily qualified for boilers.

• Search the register before they visit, using the business name or number they gave you.
• Check the card on the day, including the expiry date.
• Check the back of the card for the specific qualification that covers your job.

Source: Gas Safe Register

Get three quotes, and make them comparable

One quote tells you nothing, because you have no idea whether it is high. Three tells you where the middle is.

The mistake is comparing headline numbers. Ask every installer to put the same things in writing: the boiler make, model and output, whether a system flush is included and which kind, whether the gas supply pipe needs upgrading, the warranty and its conditions, and how many days the job will take.

The questions that separate good from cheap

• Are you accredited by the manufacturer of the boiler you are quoting? This often determines whether you get the longest warranty.
• What is excluded from this price? The honest answer usually mentions making good, and possibly the gas supply pipe.
• Who registers the installation with Building Control? It should be them, via Gas Safe, and you should receive a compliance certificate.
• What happens if you find something unexpected on the day? You want a process, not a shrug.
• Can I see recent work nearby, or reviews from this year?

Warning signs

• Cash only, or a large deposit up front. A deposit for materials is normal; most of the money before any work is not.
• Pressure to decide today, or a discount that expires this evening.
• No written quote, or one that is a single line and a single number.
• Reluctance to show the Gas Safe card, or a card whose back does not cover boiler work.
• A price far below the other two. Either something is excluded, or someone has not looked properly.

Are online reviews worth anything?

Some. Read the three-star ones, which tend to be the most honest, and look at how the business responds to complaints rather than how many five stars it has.

Recency matters more than volume. A firm with two hundred reviews from four years ago and nothing since has changed, and possibly changed hands. Twelve detailed reviews from this year tell you more.

Be sceptical of a wall of identical short five-star reviews posted within days of each other. Fake reviews are a banned practice under the Digital Markets, Competition and Consumers Act 2024, and the pattern is usually easy to spot.

Should you use a national company or a local installer?

National firms tend to cost more and offer more process: a fixed price online, a call centre, a standard warranty. Local independents are usually cheaper and the person quoting is often the person fitting, which means fewer things get lost between the two.

Neither is inherently better. What matters is Gas Safe registration, a written quote you can compare, and whether they turn up when they say they will. Get one of each among your three quotes and you will learn a lot from the difference.

What if something goes wrong afterwards?

Two separate things cover you, and they are worth understanding before you need them.

The manufacturer's warranty covers the boiler itself, subject to registration and annual servicing. The installer's workmanship guarantee covers the installation: pipework, flue, and anything fitted incorrectly. Ask how long the workmanship guarantee lasts, because it varies considerably and is often much shorter than the boiler warranty.

If a dispute cannot be resolved directly, an installer registered with a consumer protection scheme will have a complaints process attached. Ask which scheme they belong to before the work starts, not after.

After the job

You should receive a Building Regulations Compliance Certificate, the boiler's warranty registration, and the manufacturer's paperwork. Keep all of it: you will need the warranty documents for any claim, the annual service records to keep the warranty valid, and the compliance certificate when you sell the house.