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ComGas Services UK Ltd
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Boiler Servicing

Annual Boiler Servicing

An annual service checks that your boiler is burning gas safely and efficiently, and catches wear before it causes a breakdown. Carried out by Gas Safe registered engineers with a full combustion analysis and written record, for homeowners and landlords across Farnham, Guildford, Godalming, Farnborough, Fleet and Camberley.

Planned boiler maintenance

A running boiler still needs a proper annual check.

A boiler that is running does not necessarily mean that it is running safely or efficiently. Seals degrade, burners collect debris, heat exchangers pick up deposits, and safety devices can drift out of correct operation gradually, with no obvious symptom until something fails outright.

An annual service catches that drift early, while it is still a minor adjustment rather than a replacement part or a shutdown. It also provides the documented maintenance history that homeowners, landlords and warranty providers may need.

ComGas Services UK Ltd
Gas Safe · OFTEC · REFCOM F-Gas · CHAS · Constructionline

What a proper service includes

Checks and measurements, not a visual glance and a sticker.

A genuine service is a set of checks and measurements. We inspect the boiler, test safe operation and record the readings taken so that any findings can be properly understood.

Combustion, Gas and Safety Checks

The service starts with measured checks that show whether the boiler is burning gas correctly and operating within the manufacturer's specification.

  • Combustion analysis (flue gas analysis)
  • Gas rate checked against the manufacturer's specification
  • Working pressure checked and adjusted if outside tolerance
  • Flue integrity and terminal position checked
  • Safety devices tested, including flame supervision and overheat protection
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Boiler Condition Checks

Wear and restriction can develop gradually. The service looks at the components and water-side condition that can affect reliability and performance.

  • Case seals and casing integrity inspected
  • Heat exchanger and burner inspected and cleaned as required
  • Condensate trap and pipework checked for blockage or restriction
  • Expansion vessel pressure checked and recharged if low
  • System water pressure checked and topped up if needed
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Written Service Record

Every service includes a written record of the checks and readings taken, including the combustion analysis result. Keep it as a maintenance history and as evidence for a warranty claim where needed.

  • Recorded combustion analysis result
  • Documented service checks and readings
  • Maintenance history for the property
  • Evidence supporting manufacturer warranty conditions
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Annual Service Plans

A service plan puts the annual service on a fixed schedule so it is not missed between house moves, tenancy changes or a busy year. It is a scheduling convenience, not a different scope of work.

  • Annual reminder and booking pattern
  • Suitable for a single home or managed portfolio
  • Full service checks on every visit
  • A service can be carried out alongside a landlord gas safety check where relevant
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Measured evidence, clear decisions

Combustion analysis makes the safety check measurable.

The flue gas analyser measures the gases in the exhaust — principally oxygen, carbon dioxide and carbon monoxide — to confirm the boiler is burning gas completely and safely. A result outside the manufacturer's tolerance can point to a burner, gas valve or ventilation problem requiring investigation.

A boiler service and a landlord gas safety check (CP12) are not the same. A CP12 is a statutory annual safety check of every gas appliance in a rented property; a service is manufacturer-recommended maintenance focused on the boiler's performance and warranty conditions. Both can be completed on the same visit where relevant.

  • Recorded flue gas readings, rather than an assumption that the boiler has passed
  • Manufacturer-recommended annual maintenance supporting warranty conditions
  • Clear distinction between a boiler service and a landlord CP12
  • Safety or reliability findings identified before they become a larger problem
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Boiler servicing questions

Frequently asked questions.

If your boiler already has a fault, such as a lockout code, no heat or low pressure, it should be booked as a diagnostic repair visit rather than waiting for a scheduled service.

Call 01252 214120
How often should a boiler be serviced?

Once a year, in line with manufacturer requirements for most warranties. Servicing annually, even on an older boiler with no warranty condition attached, is the most reliable way to catch wear before it causes a breakdown.

Is a boiler service the same as a landlord gas safety check?

No. A service is manufacturer-recommended maintenance on the boiler itself. A landlord gas safety check (CP12) is a statutory check of every gas appliance in a rented home. Both can be carried out on the same visit where relevant.

What happens if I miss a year's service?

Undetected wear can continue longer than it should, and a missed service can affect a manufacturer warranty claim if a fault later occurs. It is still worth booking the next service; it should simply be treated as due.

Will a service fix a fault my boiler already has?

Not necessarily. A service is a planned check and clean, not a diagnostic repair visit. If the boiler has a fault, such as a lockout code, no heat or low pressure, it should be booked as a repair call rather than waiting for a scheduled service.

Do you provide written proof of the service?

Yes. Every service includes a written record of the checks and readings taken, including the combustion analysis result, which should be kept for warranty purposes and as a maintenance history for the property.

Can I put my service on a fixed annual schedule?

Yes. A service plan schedules and reminds you of the annual visit rather than leaving it to be booked ad hoc. The scope of the visit itself is unchanged.

How long does a typical service take?

A standard domestic boiler service usually takes under an hour, though this can vary if the engineer identifies something that needs a closer look or a repair quote.

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Due an annual service, or setting one up for the first time?

Tell us your boiler make and model and we'll confirm what a full service on it involves and get you booked in.

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