Short answer: A Vaillant boiler should be serviced once a year by a Vaillant or other Gas Safe registered engineer, following Vaillant's instructions, to keep the guarantee valid. The service covers gas pressure, burner, heat exchanger, seals, condensate trap, flue and a combustion test. On London's hard water, ecoTEC combis also need a hot water flow check.
Vaillant ecoTEC boilers are everywhere in London, from riverside flats in Battersea to Edwardian houses in Ealing. Vaillant search terms are among the most common boiler searches in the city. If you have one, here is what a service should involve and what Vaillant’s guarantee asks of you.
What Vaillant’s guarantee says
Vaillant’s domestic boiler guarantee terms say the boiler must be serviced annually by a Vaillant or other Gas Safe registered engineer, in accordance with the manufacturer’s instructions. The cost of the annual service is not included in the guarantee. If the guarantee becomes void, Vaillant may offer an extended guarantee product at an extra cost.
Guarantee lengths
Vaillant’s own guarantee tables, for installers, list different terms by model:
| Model | Standard guarantee | With registered installer |
|---|---|---|
| ecoTEC plus | 5 years | Up to 8 years, or 10 with a Vaillant filter |
| ecoTEC pro | 2 years | 7 years |
| ecoFIT pure | 2 years | 7 years, or 10 with a Vaillant filter |
| ecoTEC exclusive | 5 years | Up to 8 years, or 10 with a Vaillant filter |
These come from Vaillant’s installer guarantee information and depend on the installer’s membership level. Your certificate shows your actual term. If your guarantee mentions a Vaillant filter, keep a record of each filter clean.
What the service covers
| Check | Why |
|---|---|
| Gas working pressure | Correct burning |
| Burner and heat exchanger | Inspected and cleaned to Vaillant’s steps |
| Seals and gaskets | Vaillant may require certain seals to be replaced when parts are removed |
| Ignition and flame sensing electrodes | Worn electrodes cause F28 lockouts |
| Condensate trap | Cleaned, as a blocked trap stops the boiler |
| Fan and flue | Safe removal of fumes |
| Combustion test | Readings compared with Vaillant’s figures |
| System pressure and expansion vessel | Low pressure causes F22 |
| Pump and pressure sensor | Faults show as F75 |
| Hot water flow (combis) | Scale check on hard water |
Our post on Vaillant fault codes explains F22, F28 and F75.
Hard water and ecoTEC combis
Thames Water says all the water in its region is hard. ecoTEC combis heat tap water through a plate heat exchanger, and scale builds up there over time. At the service, the engineer runs a hot tap and checks flow and temperature, and checks any scale reducer on the cold feed.
Battersea flats with Vaillant combis
Many flats in Battersea, especially newer riverside blocks, have compact Vaillant combis in kitchen or utility cupboards. Some have flues running through ceiling voids. The HSE flues in voids guidance says these must be inspectable through hatches. Without them, the engineer must treat the boiler as at risk. Our Battersea area page covers the housing there.
If you live in a block with a communal heat network, you may not have a Vaillant boiler at all, but a heat interface unit. Check before booking.
Finding your model
The model name is on the front panel, such as ecoTEC plus 832 or ecoTEC pro 28. The data badge, usually under the front cover, shows the full model and serial number. The serial number tells Vaillant the date of manufacture.
Warranty repairs
If your Vaillant breaks down while in guarantee, Vaillant asks owners to book repairs through its own service line. Keep your service records ready. Servicing can be done by any Gas Safe registered engineer following Vaillant’s instructions.
The Benchmark record
At the back of the installation manual is the Benchmark checklist. Its service section should be filled in at every service. Keep the manual with the boiler, or keep a copy, along with the separate service records.
When to book
Book about 12 months after the last service. Spring and summer are easiest. London search data shows demand for boiler services in October at about four times the level of May and June. See our post on the best time to book.
Common Vaillant faults a service catches
Several of the faults behind the most searched Vaillant codes are found at a yearly service before they stop the boiler. A blocked condensate trap or worn electrode can lead to F28 lockouts. A flat expansion vessel or slow leak can lead to F22 low pressure. Sludge or air around the pump can lead to F75. The engineer checks each of these as part of the service.
If your guarantee mentions a Vaillant filter, the filter clean should be recorded too. Our post on magnetic boiler filters explains why filters matter.
Getting ready for the visit
Clear the cupboard around the boiler, find the manual with the Benchmark checklist, and note the model from the front panel. If the boiler is in a block with a concierge, register the engineer in advance. If the flue goes into the ceiling, clear furniture from under any inspection hatches.
Booking
On our boilers we service page you can book a Vaillant service. Tell us the model, its age, where it is, and the date of the last service.
Gas work in the UK must be done by a Gas Safe registered engineer. Check the ID card and the Gas Safe Register.
Quick questions
Does Vaillant have to service my boiler?
No. Vaillant says a Vaillant or other Gas Safe registered engineer can service it, following its instructions.
How long is a Vaillant guarantee?
It varies. Vaillant's own tables show standard guarantees of 2 or 5 years on different ecoTEC models, with longer terms through registered installers.
Is the service included in the guarantee?
No. Vaillant says the cost of annual servicing is not included.
Last updated 23 October 2026. Written for homes in London. Rules can change, so check the linked sources for the latest position.