What Does a Heating Engineer Do and When Should You Call One?

If your hot water cuts out or the radiators stay cold despite the thermostat being on, your first instinct might be to call a plumber. But depending on the issue, it’s often a heating engineer you actually need. Understanding what a heating engineer does (and when to call one) can save time, money and disruption. 

What does a heating engineer do? 

A heating engineer installs, maintains and repairs heating systems such as boilers, radiators and underfloor heating. They work across domestic and commercial properties, helping with everything from annual servicing to full system installations. 

If you're replacing an old boiler, dealing with poor system pressure, or simply planning a heating upgrade, it's a heating engineer you'll want. 

What’s the difference between a heating engineer and a plumber? 

While plumbers deal with water systems like taps, toilets and sinks, heating engineers work specifically with heating systems. That includes boilers and gas appliances, which require specialist training. 

Some professionals do both (you'll often see "plumbing and heating engineer" listed together), but not every plumber is qualified to work on heating. Always check if someone is Gas Safe registered before allowing them near your boiler. 

Can a plumber fix a boiler? 

Only if they’re also a heating engineer and registered to work on gas appliances. Many aren’t. Boilers are complex and involve gas, pressure and electrics and is not something to be handled by anyone without the right expertise. For anything beyond topping up pressure or bleeding a radiator, it’s best to call a qualified heating professional. 

Common problems heating engineers deal with 

Heating engineers are regularly called out for: 

• No heating or hot water 

• Low boiler pressure 

• Cold or uneven radiators 

• Leaking boilers 

• Thermostat faults 

• Routine servicing 

They also handle system upgrades and new installations. If you're switching to a more energy-efficient setup or need advice on modern controls, a heating specialist can guide the process. 

When should you contact a heating engineer? 

Any time your heating or hot water stops working properly. Strange boiler noises, a persistent loss of pressure, or radiators that won’t heat evenly are all signs that something’s wrong. Many modern boilers also display error messages that an engineer can then use to diagnose an issue.

What qualifications should a heating engineer have? 

At minimum, they must be Gas Safe registered to work on gas systems in the UK. You can check their ID on the Gas Safe Register. Most will also hold NVQ Level 2 or 3 qualifications in plumbing and heating. Many have extra training from boiler manufacturers/gas companies too, which helps when diagnosing specific models or set ups. 

(If in doubt, always ask. A good engineer will be happy to show you their credentials.) 

Need help with your heating system? 

Contact Onyx Solutions today for expert advice, fast call-outs, and trusted heating engineers near you. Whether it’s a one-off repair or ongoing support, we’re here to keep your home warm and running efficiently.