Are Radiators Checked in a Boiler Service? What a Service Doesn't Cover

No, a standard boiler service does not include checking every radiator. The engineer checks the system pressure and may notice obvious problems such as a leak near the boiler, but bleeding, balancing or inspecting each radiator is not part of the service. A boiler service is a check of the boiler: its internal components, burner, flue, combustion and safety devices. Repairs, replacement parts, power flushing, other gas appliances, a landlord gas safety certificate and the hot water cylinder all sit outside a standard service unless you ask for them. Knowing where the line falls helps you book the right visit and compare quotes fairly.

What a Standard Boiler Service Does Cover

A boiler service covers the boiler and its flue. The engineer inspects and cleans the internal components, analyses combustion, checks the flue and ventilation, tests the safety devices and confirms the boiler is working as the manufacturer intends.

Many engineers also check the system pressure and the expansion vessel charge on sealed systems, because both affect how the boiler runs. At the end you should get a written record of what was checked. Our article on what a Gas Safe engineer checks during a service goes through each step. Everything below is what usually falls outside it.

Radiators and the Wider Heating System

Radiators, pipework, valves and zone controls are part of the heating system, not the boiler, so they are not normally covered. An engineer may point out something obvious, but they will not work through each radiator on a service visit.

If you have radiators that stay cold at the bottom, rooms that never warm up, or a system that keeps losing pressure, those are system questions. They need someone to look at the whole circuit, not just the boiler. A central heating health check is designed for that: it looks at radiators, valves, controls and the condition of the system water alongside the boiler.

Repairs and Replacement Parts

A service is an inspection and clean, not a repair. If the engineer finds a fault or a worn part, the fix is normally quoted separately rather than done as part of the service price.

This is the most common source of confusion over the final bill. A service may show that a seal, a fan, a sensor or a valve needs replacing. A good engineer will explain what they found, whether it is urgent, and what the repair involves, and let you decide before anything extra is done. If the fault makes the boiler unsafe, they may need to turn it off until the repair is made. Ask before booking how the company handles faults found during a service, so there are no surprises.

Power Flushing and System Cleaning

Power flushing is a separate job, not part of a service. A service does not clean sludge out of the radiators and pipework.

An engineer may recommend a flush if they see signs of sludge, such as dirty system water, cold spots at the bottom of radiators or a blocked filter. It takes several hours and specialist equipment, so it is booked on its own. Our guide to central heating power flushing explains when it is worth doing and when it is not.

Other Gas Appliances and the Gas Safety Certificate

A boiler service only covers the boiler. Your gas hob, cooker, gas fire or gas water heater are not checked unless you ask for them, and a boiler service is not a Landlord Gas Safety Certificate. A gas fire needs its own yearly check: see how often a gas fire should be serviced.

If you are a landlord, the annual gas safety check (CP12) must cover every gas appliance you provide, and it produces a specific record that a service does not. The two are often done on the same visit, but they are different jobs and should be booked as such. Our page on the Landlord Gas Safety Certificate sets out what that inspection covers. Homeowners can also ask for other gas appliances to be checked while the engineer is there. Just say so when booking.

Hot Water Cylinders and Heating Controls

If you have a system or regular boiler with an unvented hot water cylinder, the cylinder has its own annual service, which is not part of the boiler service. Heating controls, such as the room thermostat and timer, are usually only checked to confirm the boiler responds to them.

An unvented cylinder holds hot water under pressure and has its own safety valves, which need checking by an engineer qualified for unvented systems. Combi boilers do not have a separate cylinder, so this only applies to homes with a stored hot water tank. If you are not sure which you have, a cylinder is usually a large insulated tank in an airing cupboard, and an unvented one will have pipework, valves and often a small expansion vessel attached. For controls, if a thermostat reads wrongly or a timer loses its settings, that is a separate investigation rather than something a service will fix.

How to Make Sure You Get What You Need

Tell the company about your whole setup when you book, and ask exactly what their service includes. A clear list before the visit prevents both gaps and unexpected charges.

Useful details to give are the boiler's make, model and age, whether you have a hot water cylinder, any other gas appliances, any problems you have noticed with radiators or pressure, and whether you need a gas safety certificate. With that information, the visit can be planned to cover what you actually need in one appointment, rather than finding out afterwards that part of the job was never booked.