When is the best time of year to get your boiler serviced?

Most people think about their boiler on the first cold evening of the year. That is exactly why autumn is the hardest time to get one serviced. If you can choose, book in spring or summer.

What the London search data shows

We looked at Google Keyword Planner figures for searches made in London for the phrase “boiler service london”. The pattern is clear.

Month	London searches for “boiler service london”
October 2025	1,600
November 2025	1,300
December 2025	880
January 2026	1,300
February 2026	720
March 2026	880
April 2026	480
May 2026	390
June 2026	390
July 2026	480
August 2026	590
September 2026	720

October demand is about four times the level of May and June. The wider phrase “boiler servicing” shows the same shape, with 3,600 London searches in October 2025 and 880 in each of May and June 2026.

The jump has a simple cause. The heating goes on, something does not work, and people search for help. Breakdowns and services end up competing for the same engineers’ time.

Why spring and summer work better

More choice of days

When fewer people are booking, it is easier to get the day and time that suits you. That matters if you work long hours, or if you are a landlord fitting visits around tenants.

Problems found before you need heat

A service is when an engineer finds a worn seal, a blocked condensate trap, a failing expansion vessel or a pump on its way out. Find those in July and you can fix them at your own pace. Find them in November and you are without heating while you wait for a part.

A hot water test that still means something

London’s water is hard. Thames Water says all the water in its region is hard because it passes through chalk and limestone. In a combi, scale builds up in the plate heat exchanger that heats your tap water. In summer you use the boiler mainly for hot water, so problems on that side are easy to describe and test. Our combi boiler service page explains what the engineer checks.

But what about the warranty date?

Most boiler warranties ask for a yearly service. Worcester Bosch says yearly servicing must be completed each year to keep its guarantee valid. Vaillant says the boiler must be serviced annually. If your boiler was fitted in December, your service falls in December.

You do not have to stay stuck there. Book each service a little earlier than the last, a few weeks at a time, and the date gradually moves into the quieter months. Do not jump straight from December to the following June if your guarantee terms are strict about 12 months, because a gap longer than a year could cause problems. Moving earlier is safer than moving later. If in doubt, check your guarantee certificate or ask the maker.

Our post on missed services and warranties quotes each maker’s terms.

Landlords: the two month window

Landlords have more freedom. Under the 2018 amendment to the Gas Safety (Installation and Use) Regulations, a landlord gas safety check can be done up to two months before it is due while keeping the original expiry date. The HSE explains the rule.

So if your record runs out at the end of November, a check from the start of October keeps the end of November expiry date. That helps, but it still lands in the busy months. Some landlords choose to reset the cycle once, accepting a slightly shorter year, to move all their properties into summer. See our post on renewing a gas safety certificate early.

Which homes should book earliest

Some London homes benefit most from a spring or summer slot.

• Flats with hidden flues. Many flats built since 2000, including riverside blocks in Battersea and Nine Elms, have flues running through ceiling voids. If inspection hatches have not been fitted, an engineer cannot fully check the flue. Booking early gives time to sort hatches with your managing agent. Our Battersea area page explains more.
• Older houses with sludge. Open vented systems in Victorian and Edwardian houses often collect black sludge in radiators. A summer service and filter clean gives time to plan a clean or flush if needed.
• Boilers in lofts. Lofts are hot in summer but at least dry and light. In winter, cold lofts can freeze condensate pipes and make work slower.

What to do now if it is already autumn

If you are reading this in October or November and your boiler is due, book anyway. A service in autumn is far better than no service. Give the company as much detail as you can when booking: make and model, age, last service date, and where the boiler sits. That helps them plan.

If your boiler shows any warning signs, such as yellow flames, soot around the case, or a carbon monoxide alarm sounding, do not wait for a service slot. Turn the boiler off and get it checked. If you smell gas, call the National Gas Emergency Service on 0800 111 999.

How to remember next year

The simplest way to keep your service in the quiet months is to book the next one before the engineer leaves. Put a reminder in your phone for 11 months’ time. Landlords with several properties can keep a simple list of addresses and due dates and book each two months ahead.

You can book an annual boiler service with us for any month. Spring and summer just give you the widest choice.