heating
Boiler repair and servicing
An annual boiler service costs £70 to £120, and a repair typically lands between £150 and £450 depending on the part. Two of the commonest winter faults, a frozen condensate pipe and a pressure drop, can often be fixed without an engineer at all.
What this covers
What it costs. An annual boiler service is £70 to £120. Full cost breakdown.
What the job covers
- Diagnosing fault codes and lockouts
- Annual services and warranty servicing
- Replacing diverter valves, PCBs and pumps
- Clearing blocked condensate pipes
- Repressurising and fault-finding on sealed systems
What is involved
A service is a check, not a clean-out. The engineer reads the flue gases with an analyser, checks the gas rate against the data plate, inspects the heat exchanger, burner and seals, tests the safety devices, and confirms the flue terminal and its clearances. The reading goes on a service record, and on a boiler still under warranty that record is what keeps the warranty alive. Skipping a year to save £90 can cost a £600 heat exchanger.
Repairs cluster around a short list. A diverter valve that has stuck gives heating but lukewarm water, or hot water only when the heating is on. A failed expansion vessel shows as pressure that climbs when the boiler fires and drops back overnight. A blocked condensate trap gives a gurgle and a lockout. A pump that has seized after a summer of standing still gives an overheat fault on the first cold morning of the year. Each has a characteristic symptom, which is why a good engineer asks questions before opening the case.
Two faults are worth trying yourself. A condensate pipe that has frozen where it runs outside will lock the boiler out, and pouring warm, not boiling, water along it usually clears it. A boiler showing low pressure needs the filling loop opening until the gauge reads about 1.2 bar cold. If the pressure falls again within days, there is a leak or a failed vessel and that does need an engineer.
Diagnosing fault codes and lockouts, one of the jobs a boiler repair specialist is hired for.
Choosing someone for the job
Ask whether the service includes a flue gas analysis and a printed record, because some cheap services are a visual check and nothing more. Ask whether the engineer carries common parts for your make. Check the Gas Safe registration number on the card against the register, which also shows which categories the engineer is qualified for.
Common questions
How often should a boiler be serviced?
Once a year, and manufacturers make it a warranty condition. Book it in late summer: engineers are quieter, and a fault found in September is a booking rather than an emergency.
Why does my boiler keep losing pressure?
Either a leak somewhere on the sealed system, often a radiator valve or a hidden pipe joint, or a failed expansion vessel. If the pressure rises sharply when the boiler is hot and drops back cold, suspect the vessel.