ATAG vs Worcester Bosch, Vaillant, Ideal and Baxi: comparing boiler brands

We don't get paid more to recommend one boiler brand over another, so here's our honest, engineer's-eye comparison of the boilers we install most across London — including one most homeowners haven't heard of, and why we rate it highly enough to fit as standard on our Standard and Premium packages.

Meet ATAG, our Standard and Premium boiler of choice

ATAG is a Dutch manufacturer, not a household name in the UK the way Worcester Bosch is, but it's one of the highest-quality boilers on the market. A few reasons we specify it:

• Dutch engineering: ATAG builds its own stainless steel heat exchangers in-house rather than buying in a mass-produced part, which is the main reason it can back them for so long.
• Up to 98% efficiency: among the most efficient combi boilers sold in the UK, which shows up as a lower gas bill.
• Market-leading warranty: up to 18 years on the boiler, longer than any of the well-known UK brands offer, plus a lifetime warranty on the heat exchanger itself, the single most expensive part to replace.
• OpenTherm compatible: works with modulating smart controls (see our smart thermostats and OpenTherm guide) for steadier temperatures and better efficiency than a basic on/off thermostat.

The trade-off is brand recognition — you won't see it advertised on television the way you will Worcester Bosch. We think the engineering and the warranty more than make up for that, which is why it's what we fit on our Standard and Premium packages rather than a mass-market alternative at the same price point.

How it compares to the brands you've heard of

• Worcester Bosch — up to 12 years' warranty with annual service. The brand we fit most at Essential tier. Excellent parts availability and a strong reputation with landlords and buyers.
• Vaillant — up to 10 years' warranty. Well engineered and quiet running, a strong choice for larger households with higher hot water demand.
• Ideal — up to 12 years' warranty. Good value without much compromise on reliability, a sensible budget-conscious choice.
• Baxi — up to 10 years' warranty. British-made, strong option where cupboard space is genuinely tight.

All four are consistently rated among the most reliable combi boilers on the UK market by independent surveys, and we're happy to fit any of them at Essential tier. None currently match ATAG's warranty length, which is the main reason we've made it our Standard and Premium boiler.

Warranty length: read the small print

Whichever brand, the headline warranty usually only applies if the boiler is serviced annually by a registered engineer, and often only if it was installed by an accredited installer for that brand. We're accredited for all the brands above, so when we quote a warranty length, it's the one you'll actually get. Our Boiler Care plan handles the annual service automatically, so the warranty never lapses because a reminder got missed.

Our recommendation

For most London homes, our Standard package with an ATAG boiler is the sensible middle ground: a genuinely premium boiler, a 12-year warranty, at a price close to what other installers charge for a mainstream brand with half the cover. Premium adds another six years plus lifetime heat exchanger cover for a modest step up in monthly cost — see the breakdown in our instant quote tool. Essential remains a solid, cheaper option if you're planning to move house within the warranty period.

Whichever package you're leaning towards, get a fixed price for your home in a couple of minutes. Get your instant boiler quote.