Worcester Bosch and Vaillant both make reliable, well-supported combi boilers, and for most homes the choice between them matters less than getting the right model, the right size and a good installation. Pick on the specific model, its guarantee terms through your installer, the controls you want, and how well it fits your space.
We are not tied to either brand in this guide. What follows is based on what each manufacturer publishes on its own website, with links at the bottom so you can check the current details yourself.
The two brands in brief
Worcester Bosch is part of the Bosch group and is based in Worcester. Its gas combis sit under the Greenstar name, and the company says there are more than two million Greenstar combi boilers in UK homes. It also makes oil and LPG boilers, which matters if you are off the gas grid.
Vaillant is a German manufacturer. Its main gas boiler range is the ecoTEC family, with the ecoTEC plus as the core combi and system model, now in a remastered version.
Combi ranges compared
Ranges change, so treat this as a snapshot of what each manufacturer lists on its site at the time of writing.
| Worcester Bosch | Vaillant | |
|---|---|---|
| Main combi ranges | Greenstar 1000, Greenstar 4000, Greenstar 8000+, plus a Lifestyle range and a compact range | ecoTEC plus (remastered), plus other ecoTEC models |
| How they position them | 1000 for smaller homes, 4000 for medium homes, 8000+ as the premium model | ecoTEC plus combi in 26, 32, 36 and 40kW outputs |
| Connected controls | Worcester Bosch controls (check compatibility with the model) | myVAILLANT connect |
| Notable feature claimed | Weather compensation on some Greenstar models | IoniDetect combustion technology |
| Fuel options | Gas, with oil and LPG models also listed | Gas; some ecoTEC plus outputs are LPG adaptable (not the 40kW models) |
| Published guarantee example | Greenstar 8000+: up to 12 years when fitted by a Worcester Bosch Accredited Installer with a Greenstar system filter | ecoTEC plus: 5 years standard, extendable up to 10 years when fitted by a myREWARDS installer and registered with a Boiler Protection Kit |
Not sure a combi is right? Both make system boilers too
If your home has two or more bathrooms in use at once, a system boiler with a hot water cylinder may suit you better than any combi. Both brands cover that. Vaillant lists the remastered ecoTEC plus as a system boiler in 10, 15, 20, 25, 30 and 35kW outputs, and Worcester Bosch has its own system and regular boiler ranges.
So the brand question rarely forces the boiler type. Decide the type first, based on how your household uses hot water, then compare models. Our combi vs system boiler guide walks through that decision, including when a cylinder is the better answer than a bigger combi.
Guarantees: read the conditions
The headline guarantee figure is the one brands lead with, and it nearly always comes with conditions. On the manufacturers' own pages:
- Worcester Bosch offers up to 12 years on the Greenstar 8000+ for homeowners who use a Worcester Bosch Accredited Installer and have a Greenstar system filter fitted. It notes that extended guarantees are not available when a System Filter Micro is fitted.
- Vaillant's ecoTEC plus comes with a 5-year standard guarantee, which can be extended up to 10 years when fitted by a myREWARDS installer, with eligibility tied to registering a Boiler Protection Kit or Advanced Boiler Protection Kit (filter).
Both brands, in other words, link their longest cover to an approved installer and a filter. Most guarantees also expect a yearly service by a registered engineer. Ask your installer which guarantee length applies to the exact model they are quoting, whether they are on the relevant scheme, and what you need to do to keep it valid.
What matters more than the brand
The right size
A well-sized mid-range boiler will serve you better than an oversized premium one. Combi size is mostly about hot water flow and your mains supply. Our guide to what size boiler you need explains how to judge it.
The installation
Most early boiler problems trace back to the installation, not the box: dirty system water, a poorly run condensate pipe, wrong gas pipe size or a badly set up boiler. A system clean, inhibitor, a magnetic filter and proper commissioning give any brand the best start.
Controls
Both brands offer their own controls, and many models work with third-party smart thermostats. If you already use Hive, Nest, Tado or Drayton Wiser, check compatibility with the exact model, and ask whether load or weather compensation is supported. Those features help a condensing boiler run more efficiently. Our smart thermostat installation page has more.
Space and position
Fitting a boiler in a kitchen cupboard? Check the dimensions and service clearances of the specific model against your space. Both brands publish these in their installation manuals. Worcester Bosch markets a compact range for exactly this.
Parts and support locally
Both brands are widely fitted across the South West, so parts and engineers who know them are easy to find. That is one of the real benefits of choosing either over a less common make.
So which should you choose?
Honestly, either. If you are off the gas grid and want one brand across oil and gas properties, Worcester Bosch's oil and LPG range is worth a look. If you like Vaillant's app and the ecoTEC plus fits your space and output needs, it is a strong choice too. Ask your installer what they fit most often and why: an engineer who installs a brand regularly knows its quirks and has the right parts on the van.
When we quote for a combi boiler installation, we recommend a specific model for your home after a survey and explain why. For more on pricing, see our new boiler cost guide, and if spreading the cost would help, our boiler finance page explains the options.
Frequently asked questions
Is Worcester Bosch better than Vaillant?
Neither is clearly better across the board. Both are established brands with good parts support in the UK. The right choice depends on the model, the size you need, the guarantee your installer can offer and the controls you want.
Which has the longer guarantee, Worcester Bosch or Vaillant?
On their own sites, Worcester Bosch offers up to 12 years on the Greenstar 8000+ through an Accredited Installer with a Greenstar filter, and Vaillant offers up to 10 years on the ecoTEC plus through a myREWARDS installer with a protection kit registered. Terms vary by model, so check the exact one you are quoted.
What sizes does the Vaillant ecoTEC plus combi come in?
Vaillant lists the remastered ecoTEC plus combi in 26, 32, 36 and 40kW outputs. The 40kW versions are not LPG adaptable, according to Vaillant.
Do Worcester Bosch make oil boilers?
Yes. Worcester Bosch's site says its combi boilers are available for gas, oil and LPG, which is useful for off-grid homes across rural Devon, Cornwall and Somerset.
Does the brand affect how long a boiler lasts?
Build quality plays a part, but servicing and clean system water matter more. Worcester Bosch and Vaillant both put a well-maintained boiler's life at around 10 to 15 years or more. See our guide on how long a boiler lasts.