Does a missed service void your boiler warranty?

Many London homeowners have a boiler with a long maker’s guarantee, sometimes seven, ten or twelve years. Those guarantees nearly always come with conditions, and the most common is a yearly service.

What each maker says

These quotes come from each maker’s own pages, checked in October 2026. Terms change and depend on the model and when it was installed, so always read your own certificate.

Maker	What they say
Worcester Bosch	Yearly servicing is a condition of our manufacturers guarantee and must be completed each year to keep your guarantee valid. Services must be carried out by a Gas Safe registered engineer for gas boilers
Vaillant	The boiler must be serviced annually by a Vaillant or other registered Gas Safe Registered engineer in accordance with the manufacturer’s instructions. The cost of servicing is not included
Baxi	The 800 range 10 year warranty is subject to registration within 30 days, the Benchmark checklist, an annual service and the supplied magnetic filter being maintained
Ideal	Warranties run from 2 to 12 years, and may be limited to 12 months if not registered within 30 days. Check your certificate for servicing terms
Viessmann	Product must be registered and serviced annually to qualify beyond the first year
Glow-worm	Register within 30 days of installation. Check your certificate for servicing terms

What counts as a service

The maker wants a service done to its instructions by a Gas Safe registered engineer, and recorded. In practice that means:

• The case off and the inside inspected and cleaned
• A combustion test with the readings written down
• The Benchmark service record in the back of the manual filled in
• A written service record kept by you

A quick visual check does not count. Neither does a landlord gas safety check on its own, which checks safety but is not a service. See our post on the gas safety check vs boiler service.

If you have missed a service

1. Book now. The sooner the gap is closed, the better your position.
2. Contact the maker. Explain the date of the last service and when the next is booked. Ask whether your guarantee is affected.
3. Keep the record. Make sure the new service is written in the Benchmark section with the date.
4. Do not backdate. A service record must show the real date. Backdating a record is dishonest and could cause bigger problems.

Some makers may be flexible about a short delay. Others are strict. If your guarantee has lapsed, Vaillant, for example, says it may offer an extended guarantee product for an extra cost.

Common reasons services get missed

• Moving house and not knowing when the last service was
• A new boiler, with the first service forgotten
• A landlord relying on the gas safety check alone
• Lockdowns, illness or simply forgetting

If you have moved into a home and do not know the service history, see our post on finding your boiler service history.

Registration matters too

Several makers need the boiler registered within 30 days of installation. If it was not registered, the guarantee may be much shorter than you think. Ideal says its warranty may be limited to 12 months without registration. Check with the maker using the serial number on the data badge.

Ealing family houses

In Ealing, many Edwardian houses have had boilers replaced in the last decade, often with long guarantees. A lot of these are system boilers with unvented cylinders, which also have their own maker conditions about yearly safety valve checks. Our Ealing area page covers the housing there. Keep the boiler and cylinder paperwork together.

Warranty repairs

If a boiler in warranty breaks down, contact the maker first. Most run their own repair service for boilers in guarantee. A repair by someone else may affect a claim. Servicing is different: any Gas Safe registered engineer following the maker’s instructions can usually do it.

Staying on track

• Book the next service before the engineer leaves
• Put a reminder in your phone for 11 months
• Keep a folder with the guarantee, Benchmark and every record
• Spring and summer slots are easier to book. London search data shows October demand at about four times May and June

New boilers and the first service

The first service is the one most often missed. A new boiler works well for a year, so it is easy to forget. Most makers expect the first service around 12 months after installation, then yearly. If your boiler was fitted in winter, the first service falls in winter too. You can move it into the quieter months over time by booking a little earlier each year, rather than leaving a gap longer than 12 months.

Booking

Our boilers we service page covers each make and what the service includes. Tell us the make, model and date of the last service when booking.

Gas work in the UK must be done by a Gas Safe registered engineer. Check the ID card and the Gas Safe Register.