What affects the cost
Cost depends on the type of system (combi vs system vs conventional), whether it's a straightforward swap or a full system change, boiler brand and output size, and property access. Moving a boiler's location, rather than replacing it in place, adds cost because of the extra pipework, flue routing and making good involved.
Red flags in a cheap heating quote
A quote well below others is worth questioning — check it specifies a named boiler make and model (not just "combi boiler"), includes a powerflush if the system is older, and states the warranty length. No Gas Safe registration number offered unprompted is a clear red flag.
What a boiler fault code usually means
Modern boilers display a fault code rather than just stopping — the exact code varies by manufacturer, but common causes include low pressure, a faulty sensor, an ignition fault or condensate pipe freezing in cold weather. Note the code and the boiler make/model before calling; it speeds up diagnosis considerably.
Common heating engineer jobs
Heating engineers install, service and repair boilers and central heating systems: annual boiler services, fault diagnosis, radiator installation and balancing, powerflushing, and full system replacements. Many also work on unvented hot water cylinders and, increasingly, heat pumps and other low-carbon heating.
Heating in older and period properties
Older properties often have narrower pipework, no cavity wall insulation, and sometimes a heating system not originally designed for full central heating throughout — all of which affect boiler sizing and radiator choice. A heating engineer working on a period property will usually assess the whole system, not just swap the boiler in isolation.
Why an annual boiler service matters
An annual service checks for gas leaks, correct combustion, and general safety, and most manufacturer warranties require it to stay valid. It's also when a heating engineer is most likely to catch a developing fault — a failing part or a a pressure issue — before it causes a breakdown, particularly in winter when boilers are used hardest.
Air source heat pumps, what to know
A heat pump extracts heat from outside air even in cold weather, and typically runs at a lower flow temperature than a gas boiler, which usually means larger radiators or underfloor heating for the same comfort level. Installation is a bigger job than a boiler swap and government grant schemes (like the Boiler Upgrade Scheme) can offset some of the cost.
What is a powerflush and do you need one?
A powerflush clears sludge and debris from radiators and pipework using a pumped chemical flush — often recommended if radiators are cold at the bottom or the system is noisy, and standard practice before fitting a new boiler onto an older system so it isn't immediately clogged.