Vaillant Boilers Review: ecoFIT, ecoTEC Ranges and Prices

Who are Vaillant?

Vaillant was founded in 1874 by Johann Vaillant in Remscheid, Germany, and the company is still headquartered there and still family owned. Its own heritage pages credit it with the first combined heating and hot water appliance (the Combi-Geyser VCW 20 of 1967), the first fan-assisted wall-hung boiler that drew combustion air from outside (1978) and its first condensing appliance, the ecoTEC, in 1995.

In the UK, Vaillant Group opened a sales and production site in Belper, Derbyshire, in 2001; the 22,000 square metre factory there builds boilers and, since 2022, aroTHERM heat pumps, and a second plant in Derby started producing uniSTOR cylinders in 2025. The group also owns Glow-worm, Saunier Duval and several other European brands, so the Glow-worm boilers built in Belper share a great deal of engineering with the Vaillant range. You will find both spellings - valiant boiler, valliant boiler - in search results; the correct one is Vaillant.

This page is the brand review; for how the ranges rank against rivals, start with our hub on the best combi boilers in the UK.

Which Vaillant boiler ranges are sold in the UK?

Vaillant uses three names: ecoFIT (value), ecoTEC (core and premium) and, on older stock, ecoTEC pro. Model numbers encode the type and output: an 8 prefix is a combi (832 = 32 kW combi), a 6 prefix a system boiler (630 = 30 kW system) and a 4 prefix an open-vent or regular boiler (430). Figures below are from Vaillant's UK product pages and datasheets; flow rates are at a 35°C rise.

The previous ecoTEC plus combi line (825, 832, 835, 838 and the 938 storage combi) was discontinued when the current range launched, but tens of thousands are still in service and spares remain available. If you own an 832 or 835, nothing here changes for you except the model you would buy next time. Vaillant's system boilers are covered in more depth in what a system boiler is and who it suits.

What are the documented strengths of a Vaillant boiler?

• Stainless steel heat exchanger on ecoTEC models. Stainless resists corrosion from poor system water better than aluminium, which is one reason the ecoTEC plus has a long reputation among engineers. The ecoFIT pure uses an aluminium heat exchanger, so it is the exception.
• Modulation. The ecoTEC exclusive turns down to a tenth of its output (1:10), and the plus range modulates widely too, so the burner runs steadily in mild weather instead of cycling on and off.
• Quiet operation. The ecoTEC exclusive carries Quiet Mark approval, useful in open-plan kitchens and flats.
• Hydrogen testing. Vaillant states its ecoTEC exclusive was tested with up to 20 per cent hydrogen blended into natural gas under the HyDeploy project.
• Controls. The sensoCOMFORT and sensoHOME controls offer weather compensation, and the myVAILLANT connect gateway adds app control. Weather compensation is one of the cheapest ways to improve real-world efficiency.
• UK presence. Design input, manufacturing and the technical helpline are in Derbyshire, and the installer base is second only to Worcester Bosch.
• Which? standing. Vaillant's product pages describe the brand as a Which? Recommended Brand for gas boilers, with 5 stars for reliability and engineer recommendations in that survey; this is the manufacturer's statement of a third-party result.

What are the weaknesses?

• Short standard guarantee on the ecoFIT pure. Two years out of the box is the shortest of any major brand's entry range. You only reach 10 years through a registered installer with the protection kit, so a cheap quote from a non-registered fitter is not the bargain it appears.
• Price. The ecoTEC plus typically costs £100-£400 more fitted than an Ideal Logic Max or Baxi 800 that comes with 10 years as standard.
• Aluminium on the budget model. The ecoFIT pure gives up the stainless heat exchanger that is the brand's main engineering argument.
• Flow restrictors. Vaillant's datasheets quote flow at a 35°C rise and a lower figure at 45°C achieved with a flow restrictor; owners replacing an old high-flow combi with a 26 or 32 kW plus sometimes notice less hot water than they expected. Choose the output on flow rate, not on the old boiler's number.
• Range churn. The plus line has been renumbered more than once, which makes second-hand advice and some online reviews out of date.

Who does a Vaillant combi boiler suit?

Before fixing on an output, run through our boiler size guide and calculator; the hot water figure, not the heating figure, decides a combi.

How much is a Vaillant boiler?

Typical 2026 prices from national installers and merchants are below. Boiler-only excludes flue, filter, controls and labour; fitted assumes a like-for-like combi swap.

Extras that push a quote up: a vertical or extended flue, a 22 mm gas pipe upgrade, a powerflush (£300-£800), smart controls (£120-£250 fitted) and a conversion from a regular or system boiler (£500-£1,500 more). Our guide to boiler prices by brand compares these bands with Worcester Bosch, Ideal and Baxi, and boiler installation costs, labour and extras explains the labour side of the bill.

Which Vaillant fault codes are most common?

Vaillant codes start with F for a fault that locks the boiler out. The meanings below are summarised from Vaillant's published fault code list and operating instructions, and the first-aid steps are limited to what a householder can safely do.

Each of the big three has its own troubleshooting page: Vaillant F22 low pressure, Vaillant F28 and F29 ignition faults and Vaillant F75 pressure sensor and pump issues. For a flashing radiator symbol, a flashing "C", no hot water or questions about resetting, see Vaillant boiler problems: flashing symbols, no hot water and reset.

How do you use a Vaillant boiler day to day?

• Turning the heating on. On ecoTEC plus and ecoFIT pure models the two dials or buttons on the front set the heating flow temperature and hot water temperature; the radiator symbol lights when heating is enabled. If the heating does not come on, the room thermostat or programmer is usually the reason, not the boiler.
• Comfort mode. Keeps the heat exchanger warm for faster hot water. Turn it off in summer to save gas; turn it on in winter if you dislike the wait.
• Restarting after a lock-out. Press the reset button (the flame symbol with a cross on most models) once. Repeated lock-outs are a fault to be diagnosed, not a habit to live with.
• Turning the boiler off. Use the on/off button on the panel; only switch off at the fused spur for electrical work or a long absence, and remember frost protection stops working without power.
• Flow temperature. Most homes are comfortable with the heating dial at 60-65°C, which keeps the boiler condensing. Our guide to what temperature your boiler should be set at explains the trade-off.

How old is my Vaillant boiler?

The data plate behind the drop-down flap or on the underside carries a 28-digit serial number. On most Vaillant boilers the third and fourth digits give the year of manufacture and the fifth and sixth the week, so a serial beginning 21 1 8 would be week 18 of 2021. Vaillant customer service will confirm it if you read the full number out. By model name, the rough picture is:

Anything from the bottom row is at or beyond the end of its economic life. How long boilers last goes through the signs that a repair no longer makes sense.

How does Vaillant compare with Worcester Bosch?

The two brands are close enough that the installer matters more than the badge, but there are real differences.

Our Worcester Bosch boilers review covers the rival in the same depth, and the comparison of UK boiler brands explains the ownership behind each name. Vaillant Group's own value brand is reviewed in our Glow-worm boilers review.

How do you register a Vaillant boiler or contact Vaillant?

The installer should register the boiler and the protection kit with Vaillant within 30 days of commissioning; registration through the installer scheme is what unlocks the 10-year term. Ask for the confirmation email or letter and keep it with the Benchmark checklist and your service records, because annual servicing by a Gas Safe registered engineer is a condition of the extended guarantee.

Vaillant's UK customer service line for homeowners is 0344 736 0049 and the company is based at Nottingham Road, Belper, Derbyshire. Lost the manual? Vaillant hosts operating and installation instructions for current and discontinued models; our page on where to find boiler manuals links to the right section.

Frequently asked questions

Is Vaillant a good boiler?

Yes, by every measurable signal available to a homeowner: Vaillant offers up to 10 years parts-and-labour cover on its main ranges, fits stainless steel heat exchangers to the ecoTEC models, describes itself as a Which? Recommended Brand for gas boilers and has a UK head office and factory in Belper, Derbyshire. The main cautions are a 2-year standard guarantee on the budget ecoFIT pure and prices slightly above Ideal and Baxi.

How much is a Vaillant boiler fitted?

In 2026 a like-for-like combi swap typically costs £2,000-£3,000 for an ecoFIT pure, £2,400-£3,800 for an ecoTEC plus and £3,000-£4,500 for an ecoTEC exclusive, depending on output, flue, controls and region. Boiler-only merchant prices run from roughly £850 for a 25 kW ecoFIT pure to £2,200 for a top-end exclusive. Converting from a regular or system boiler adds £500-£1,500.

What is comfort mode on a Vaillant boiler?

Comfort mode, sometimes called warm start, keeps a small volume of water inside the combi's heat exchanger warm so hot water reaches the tap a few seconds sooner. It uses a little extra gas while the boiler is idle. Switching it off (eco) saves that gas but you wait longer and may notice a brief cold slug when you first open a tap. The setting is changed from the front panel menu.

How long does a Vaillant boiler last?

A well-installed ecoTEC that is serviced every year and protected by a filter and inhibitor commonly runs 12-15 years, and plenty of early-2000s ecoTEC plus models are still in service. The 10-year guarantee available on the plus and exclusive ranges is a reasonable guide to the design life the manufacturer is comfortable with. Skipped services and dirty system water are what shorten it.

What does the flashing radiator symbol mean on a Vaillant boiler?

On ecoTEC and ecoFIT displays the radiator symbol shows central heating mode. A steady symbol means heating is enabled and there is a demand; a flashing symbol normally means the burner is firing for heating. It is not a fault on its own. If the heating is not actually getting warm, or the symbol flashes alongside an F-code, check the pressure and the thermostat and then follow the fault code guidance.

Should I buy the Vaillant Advance boiler protection kit?

If you want the extended guarantee, yes. Vaillant's 10-year terms on the ecoFIT pure, ecoTEC plus and ecoTEC exclusive require the Boiler Protection Kit or Advance Boiler Protection Kit (a magnetic filter plus system chemicals) to be fitted and registered with the boiler. Even without the guarantee angle, a filter protects the heat exchanger and pump from sludge and is one of the cheapest reliability upgrades you can buy.

Sources and further reading

• Vaillant UK - ecoTEC plus
• Vaillant UK - ecoFIT pure
• Vaillant UK - ecoTEC exclusive
• Vaillant UK - Boiler fault codes list
• Vaillant UK - Our heritage
• Gas Safe Register - Find a registered engineer

Prices and scheme details were checked on 22 October 2026 and are shown as typical ranges. Always get written quotes from Gas Safe registered installers.