Heating Engineer vs Plumber: What Is the Difference and Who Do You Need?

The Core Distinction

The terms "heating engineer" and "plumber" are often used interchangeably, but they describe different scopes of work and different qualification requirements. A general plumber is trained to install, maintain, and repair cold and hot water supply systems, waste and drainage systems, and sanitary fittings such as baths, showers, toilets, and taps. A heating engineer specialises in boilers, central heating systems, gas appliances, and radiator circuits — and crucially, must hold Gas Safe registration to work on gas appliances. Gas Safe registration is a legal requirement, not simply a professional credential. Using an unregistered person to work on gas appliances is a criminal offence in the UK, regardless of how competent they may appear.

What Gas Safe Registration Means

Gas Safe Register replaced CORGI as the UK gas registration scheme in 2009. Every engineer on the register carries a Gas Safe ID card showing their registration number, the employer they are registered under, and the categories of gas work they are qualified to carry out. The card also carries an expiry date — you should check the date has not lapsed before any engineer begins gas work on your property. You can verify any engineer at GasSafeRegister.co.uk using their registration number. Common registration categories include domestic natural gas (the most common), LPG, cooker connections, and commercial gas. An engineer registered only for domestic natural gas should not be working on LPG appliances, and vice versa. Always check that the specific type of work you need falls within the engineer's registered categories.

What a Heating Engineer Does

A Gas Safe heating engineer can carry out the full range of work on gas boilers and central heating systems: new boiler installation, boiler service, boiler repair and fault diagnosis, flue installation and testing, gas safety certificate (CP12) inspections for landlords, radiator installation and replacement, power flushing of central heating systems, central heating system design and installation, heating control installation (programmers, thermostats, smart controls, TRVs), and pipework associated with the heating circuit. Some heating engineers also hold qualifications for unvented hot water cylinder work (G3 competence), LPG systems, and commercial heating. A heating engineer who is also a qualified plumber — as is the case with most established London heating companies — can also carry out plumbing work within the same visit, avoiding the need to book two separate tradespeople for a combined job.

What a General Plumber Does

A general plumber without Gas Safe registration can work on all cold and hot water supply and distribution pipework, sanitary fittings (baths, showers, toilets, bidets), kitchen and bathroom plumbing, waste and overflow pipework, outside taps, garden irrigation, water meters, and storage tanks. They cannot touch gas pipework, gas boilers, gas fires, or gas cooker connections. A plumber can service and repair immersion heaters, unvented cylinders (with G3 qualification), and pumped shower systems. They can also carry out work on oil-fired heating systems if they hold the relevant OFTEC qualification, which is separate from Gas Safe. In practice, many experienced plumbers also hold Gas Safe registration, blurring the distinction. When booking a tradesperson, the simplest approach is to describe the job and ask directly what qualifications they hold relevant to the specific work.

Who to Call for Common Jobs

Dripping tap, leaking pipe, running toilet, blocked drain, toilet installation, shower installation: call a plumber. Boiler service, boiler repair, boiler installation, gas safety certificate, central heating installation, radiator installation: call a Gas Safe heating engineer. New bathroom that includes a heated towel rail or a bathroom radiator: either a heating engineer who is also plumber-qualified, or coordinate a plumber and a Gas Safe engineer. Boiler breakdown with no hot water or heating: call a Gas Safe heating engineer, not a general plumber — they do not have the qualifications or specialist tools to diagnose and repair a gas boiler safely. If in doubt about which type of tradesperson a job requires, call and describe the work; a reputable company will tell you honestly whether the job falls within their scope.

Checkatrade, MyBuilder, and Gas Safe Verification

When looking for either a plumber or a heating engineer in London, independent review platforms provide useful evidence of quality. Checkatrade vets tradespeople before listing them and publishes verified customer reviews. MyBuilder similarly publishes verified reviews from homeowners. Neither platform substitutes for Gas Safe verification — always check Gas Safe registration separately at GasSafeRegister.co.uk for any gas work. A company with 50+ verified reviews on both Checkatrade and MyBuilder has a proven track record of attended jobs — a useful proxy for reliability in a market where fly-by-night operators are common.

Qualifications: NVQ, ACS, and City and Guilds

UK plumbers and heating engineers typically hold NVQ Level 2 or 3 in Plumbing and Heating, or equivalent City and Guilds qualifications. Gas Safe registration requires passing Nationally Accredited Certification Scheme (ACS) assessments in the relevant gas categories. These assessments must be renewed every five years. G3 competence for unvented cylinders requires a separate assessment. OFTEC registration for oil heating requires separate Oil Firing Technical Association qualifications. When assessing a tradesperson, asking about their qualifications is entirely reasonable — a professional will be able to cite their NVQ level, ACS categories, and Gas Safe registration number without hesitation.