The boiler is making a noise it did not make last week, the hot water is lukewarm, and the search results are full of two different job titles. Plumber. Heating engineer. Some firms use both. Some use one and clearly mean the other. It matters more than it looks, because in this country one of those trades is regulated by law and the other is not.
Plumbing is not a regulated trade
Anyone in the UK can call themselves a plumber. There is no licence, no register you have to be on, and no legal minimum qualification for fitting a tap, a bath or a radiator. That surprises people. Good plumbers usually hold trade qualifications and many belong to schemes such as WaterSafe, which covers the water regulations, and many have the extra certificate needed for unvented hot water cylinders, but none of it is compulsory for the wet side of the job. You judge a plumber's competence by reputation, by asking about qualifications, and by looking at how they handle the parts of the job where the rules do bite.
Gas work is different, and the law says so
The moment a job touches gas, the picture changes completely. It is illegal for anyone who is not on the Gas Safe Register to work on a gas boiler, gas hob, gas fire or the gas pipework that feeds them. That includes servicing, repair, replacement and disconnection. A heating engineer, in the sense the trade uses the phrase, is someone who holds that registration and works on boilers and heating systems for a living. A plumber who also does gas work will be registered too; the title on the van is not the point, the registration is.
Every registered engineer carries a Gas Safe ID card with a photograph, a licence number and, on the back, the categories of work they are qualified for. Boilers and cookers are separate categories. The register is public and free to search online by business name or licence number, and you can check the card in front of you against it. A firm that is registered will be pleased you asked. A firm that gets vague at this point is telling you what you need to know.
Which one your problem needs
Think of it by what the job touches. A dripping tap, a slow-draining bath, a leaking radiator valve, a new toilet, a replacement shower mixer, a washing machine connection: plumber. Boiler service, boiler breakdown, a new boiler, moving a gas hob, a smell of gas: Gas Safe registered engineer, no exceptions. Radiators are the grey area. Fitting or moving radiators on the water side is plumbing; anything on the boiler itself, including changing a pump inside the casing or adjusting the gas valve, is not.
Most heating breakdowns turn out to be one of the same short list of faults: low pressure, a failed diverter valve, a stuck pump, a faulty circuit board, or a frozen condensate pipe in winter. A heating engineer sees these every week and will usually diagnose on the first visit. A general plumber may be able to top up the pressure and tell you the rest is not their work, which is an honest answer but a wasted call-out.
Checking before you book
Ask on the phone whether they are Gas Safe registered and what the number is, whether they work on your make of boiler, and whether the person who quotes will be the one doing the work. Look the number up while you are still talking if you like; it takes a minute.
The listings on this site cover 3,554 plumbers, and many describe themselves as heating or gas engineers, list boiler work as a service, or both. Browse the firms near you and read what each one says it does, or describe the fault and ask for quotes. Whoever you pick for the boiler, look at the card before they take the casing off.
