What a proper service includes
- A flue gas analysis — actual combustion readings taken with an analyser, compared against the manufacturer's figures
- Checking the gas supply pressure and, where required, the gas rate
- Inspecting the burner, heat exchanger and, where accessible, the combustion chamber
- Checking all seals and the integrity of the case, which is what keeps combustion products out of your house
- Testing the safety devices and controls
- Checking the condensate trap and drain, and the flue itself inside and out
- Checking ventilation to the appliance
- Checking system pressure and the expansion vessel
- Cleaning or emptying the magnetic filter if you have one
- Written record of the readings, not just a tick
How long it should take
A genuine service on a straightforward combi generally takes somewhere in the region of half an hour to an hour, longer if the appliance needs stripping down or if there is a fault to chase.
If someone is in and out in ten minutes without an analyser probe going into the flue, you have not had a service. Ask to see the combustion readings — an engineer doing the job properly will be happy to show you and to explain what they mean.
Service, safety check, and warranty
These three get used interchangeably and they are not the same.
- A safety check confirms the appliance is safe to use. That is what a landlord's legal obligation covers.
- A service is maintenance to keep it running properly and efficiently, and it is what manufacturers require for the warranty.
- A warranty claim will usually ask you to produce a record of annual servicing. No record, no claim — which is how people end up paying for a repair that should have been free.
When to book it
Late summer and early autumn, before the heating goes back on. Everyone books in October and November because that is when faults appear, so availability is tighter and a fault found then means being without heating while it is fixed. Finding it in September means a planned repair in the warm.
Common questions
How often does a boiler need servicing?
Once a year. It is what almost every manufacturer's warranty requires, and it is when the small faults get caught before they become winter breakdowns.
Is a service worth it if the boiler is working fine?
Yes, for two reasons. It keeps the warranty valid, and combustion faults are not something you can see or smell — a boiler can be running badly and appear completely normal.
Does a service include repairs?
No. A service is inspection and maintenance. If it finds a fault, the repair is quoted separately — though catching it during a service is far cheaper than an emergency callout in January.
Related guides
Why does my boiler keep losing pressure? Landlord gas safety certificates: what you actually need What actually decides the price of a new boiler
Find someone near you
Engineers set their own travel radius, so these pages show who genuinely covers each area.
Sunderland Newcastle Gateshead South Shields Washington Durham All areas