Vaillant ecoTEC Exclusive Green iQ Combi Boiler Cost with Installation

The Vaillant ecoTEC Exclusive Green iQ is the premium combi with some impressive tech to live up to its name. Underneath the cover, stainless steel and brass components are the reason this boiler keeps running for 15-20 years whilst budget models are on their way to their second replacement. 

You’re getting the same resilient build as Vaillant’s entire ecoTEC range, but with Green iQ technology that optimises running cycles for even lower gas consumption, 10:1 modulation and Quiet Mark certified operation so you’ll forget the boiler’s even there, optional WiFi connectivity via myVAILLANT connect gateway (sold separately), and an optional 10-year maximum warranty.

So, let’s have a closer look at some of the Vaillant ecoTec exclusive combi’s specs:

Vaillant ecoTEC Exclusive Combi Product Table
	Available outputs	35kW	43kW
	Type	Combi	Combi
	Fuel	Gas	Gas
	Condensing	Yes	Yes
	Efficiency rating (%)	94	94
	ErP	A	A
	LPG compatible	Yes	Yes
	Standard guarantee	5 years*
	Max output (kW)	35	43
	Flow rate (l/min)	14.5	17.8
	Mounting	Wall-mounted
	Dimensions (mm)	720 x 440 x 406	720 x 440 x 474
	Typical price (incl. VAT)	£1,950	£2,050
	Typical installation cost (incl. VAT)	£800 – £1,400
	Total cost	£2,650 – £3,450

*Terms and conditions apply.

Vaillant ecoTEC Exclusive combi overview

The Vaillant ecoTEC Exclusive Green iQ combi is exceptionally well-built and impressively quiet, making it an ideal heating solution for homeowners who value long-term reliability and premium performance.

As an all-in-one combi boiler, it delivers both central heating and hot water directly from the mains, so you can gain some valuable space back as you wave goodbye to bulky hot water cylinders or cold water tanks in the loft. 

At 720mm high, it’s designed to fit standard kitchen cupboards whilst housing the premium components that justify the price tag.

Vaillant ecoTec Exclusive Combi Range
Model output size	House size	Bathrooms	Radiators
35kW	Medium-large homes 4 bedrooms	2	Up to 20
43kW	Large homes 4 to 5 bedrooms	2-3	Up to 25

With hot water flow rates of 14.5 to 17.8 litres per minute, the Vaillant ecoTEC Exclusive combi is well-suited to homes with two to three bathrooms. The 35kW (835) handles medium-large homes with two bathrooms comfortably, whilst the 43kW (843) can manage two to three bathrooms. With the 843’s 17.8 l/min delivering Vaillant’s highest ever flow rate and maintaining excellent pressure even when multiple outlets are running simultaneously.

Key benefits at a glance

• ErP A-rated efficiency (94%)
• 10:1 modulation ratio
• Green iQ technology for optimised running cycles
• Compatible with myVAILLANT connect gateway for WiFi control (sold separately)
• Stainless steel heat exchanger with Extra-Condense technology
• Cupboard-friendly design (720mm high)
• Ultra-quiet operation (Quiet Mark accreditation)
• LPG compatible (software conversion)
• Hydrogen-ready (certified for 20% blend)
• 85% recyclable at end of life
• tiered warranty: 5 years standard, extending to 10 years when installed by a Vaillant Advance installer with filter fitted*

Vaillant ecoTEC Exclusive combi technical specifications

Under the cover is where the ecoTEC Exclusive Green iQ really demonstrates why Vaillant has such a strong reputation in the premium heating market. 

The real superpower of the ecoTec is the combination of stainless steel heat exchanger and the 10:1 modulation ratio, enhanced by Green iQ technology. Whilst mid-range boilers may use aluminium (putting them at risk of corrosion), the ecoTEC Exclusive uses stainless steel for the heat exchanger and adds significantly more intelligent power management. 

This boiler has a mind of its own to adjust output smoothly without constant on-off cycling.

Output and efficiency ratings

The Vaillant ecoTEC Exclusive Green iQ is available in 35kW and 43kW output sizes. Both models are ErP A-rated, operating at around 94% efficiency. 

Across the range, the ecoTEC Exclusive Green iQ benefits from a 10:1 modulation ratio enhanced by Green iQ technology, this is where it differentiates itself from budget and mid-range alternatives. The modulation ratio means the boiler can reduce its output to just 3.5kW (on the 35kW model) or 4.3kW (on the 43kW model) when demand is low. For instance, during mild autumns when you need heating but not much of it, the boiler can run continuously at very low output rather than cycling on and off repeatedly.

Most budget boilers can’t modulate below 15-20% of maximum output, forcing them to switch on and off every few minutes. That constant cycling is less efficient, creates more wear on components over time, and is considerably noisier. 

The result of the ecoTEC Exclusive’s wider modulation is smoother, quieter operation, earning this little combi its QuietMark accreditation. 

Dimensions 

The ecoTEC Exclusive combi is designed to be compact yet robust. 

The 835 (35kW) model measures 720mm high, 440mm wide, and 406mm deep, and the 843 (43kW) model measures 720mm high, 440mm wide, and 474mm deep – slightly deeper to accommodate the larger heat exchanger and enhanced condensate technology. 

Both models still fit comfortably into standard kitchen cupboards with adequate room for pipework connections, so you don’t have to worry about any eye-sore boiler on show.

Components included

With the Vaillant ecoTEC Exclusive Green iQ combi, we believe the standout feature is its combination of Green iQ technology and compatibility with myVAILLANT connect gateway for WiFi control. 

Unlike many boilers that require you to purchase an additional smart thermostat, the ecoTEC Exclusive can connect to Vaillant’s myVAILLANT app via the myVAILLANT connect gateway (sold separately), allowing you to adjust heating schedules and monitor energy usage remotely using your phone.

Green iQ technology is how this Vaillant combi really earns the ‘eco’ in its name. It optimises running cycles, results in even lower gas consumption compared to standard ecoTEC models, and the boiler is highly recyclable at the end of its life. 

At the heart of the boiler is Vaillant’s stainless steel heat exchanger, a material designed for long-term durability and corrosion resistance. Stainless steel is especially important in hard-water areas where limescale buildup can significantly reduce the lifespan of aluminium heat exchangers found in budget combi boilers.

The burner system automatically adjusts based on actual demand, helping to keep heating consistent and efficient even as usage changes throughout the day, contributing to quieter operation compared to budget alternatives.

The boiler is compatible with popular smart thermostats via Vaillant’s eBUS protocol with compatible Vaillant controls for modulation. 

The 843 model includes extra condensate technology with dual condensate heat exchangers for increased efficiency. 

It’s also hydrogen-ready for up to 20% hydrogen blend, providing some future-proofing as the UK gas grid potentially transitions. 

Prices and installation costs

This price usually includes the boiler unit and standard horizontal flue. The magnetic filter is sold separately but required for the 10-year warranty. 

The flue is a critical component that safely directs combustion gases outside your home; whilst a standard side-wall flue costs roughly £100, a vertical roof flue can exceed £500 due to the increased complexity of the installation and roofing work required.

Ultimately the standard installation cost is around £1,200, which is the price we’ve used in our cost breakdown below:

Vaillant ecoTEC Exclusive Combi Costs
Output size	Unit cost (incl. flue)	Total (incl. installation)
35kW	£1,950	£3,150
34kW	£2,050	£3,250

These prices are only indicative, based on our research and actual boiler prices submitted to WhatPrice by homeowners.

To get an accurate price based on your needs, you should request quotes from at least 3 Gas Safe registered installers. They can advise you on the best boiler type for your home and give you tailored estimates to compare. 

Alternatively, you can use the WhatPrice Boiler Cost Calculator to get a guide price for your installation.

Warranty and support

The warranty is one of the strongest selling points for the Vaillant ecoTEC Exclusive Green iQ, providing a level of protection that often exceeds many competitors in this price bracket. The boiler typically comes with a warranty of 5 years standard (out of the box), 7 years with Vaillant Advance installer, 8 years with Advanced Mastertech installer, or 10 years when fitted with a filter as long as it is registered within 30 days of installation – with extended warranty matching competitors when conditions are met (Baxi 600 is 7 years, Worcester Bosch Greenstar 4000 is 7-10 years).

The extended warranty (up to 10 years) is unlocked when the unit is fitted by a Vaillant Advance installer with a filter fitted and registered through the official portal within 30 days of installation.

To keep this protection active, you must ensure the boiler receives an annual service by a Gas Safe registered engineer and that the Benchmark commissioning checklist is completed at the time of install. The magnetic filter is not included with the ecoTEC Exclusive, so it is an add-on that is required to activate the warranty – make sure to factor this into your budget.

Installation information

The installation cost for a Vaillant ecoTEC Exclusive Green iQ is typically around £1,200. However, your final price will depend on a few key factors. 

If you’re doing a straightforward swap in the same location with minimal pipework changes, costs stay on the lower end. 

If your engineer needs to relocate the boiler, upgrade old pipework to meet current Gas Safe standards, or navigate a tricky flue position through a roof, the labour time and the price will naturally increase.

What to expect on installation day

If additional work is required – such as upgrading pipework or relocating the boiler – your installer should explain this clearly beforehand, including any impact on cost or installation time.

Do you need a system flush or filter?

Yes, under UK Building Regulations, it is now a mandatory requirement to fit a magnetic filter when installing a new boiler. A system flush isn’t legally required, but it’s strongly recommended if you’re replacing an older boiler, and many manufacturers (including Vaillant) make it a condition of their extended warranty.

A flush removes sludge (iron oxide and other debris) that has built up over the years in your radiators and pipework. To keep your new ecoTEC Exclusive running smoothly and protect that valuable 10-year warranty, your installer must ensure your purchased magnetic filter is fitted.

Whilst both options offer excellent protection for your heating system, they do involve extra costs. As a guide, a system flush typically costs between £350 and £800, and a filter between £65 and £300, depending on your setup.

Finding a Gas Safe registered engineer

All installers must be Gas Safe registered by law, but choosing an engineer with specific Vaillant Advance training is the best way to ensure your 30-day registration window and extended warranty is handled correctly.

Reviews and ratings

Vaillant holds a rating of 4.5 out of 5 stars on Trustpilot in the UK. With over 22,700 reviews, their score reflects a very high level of consistent quality across their product range.

We’ve collated reviews specifically relating to the Vaillant ecoTEC Exclusive Green iQ, and the feedback reveals a few consistent themes that emerge after homeowners have lived with the boiler for a year or two. Here’s what you can realistically expect:

Positive reviews

Owners of the ecoTEC Exclusive are consistently impressed by its performance straight out of the box. Quiet operation comes up repeatedly, one reviewer with the 843 model noted it was “hardly there” in terms of noise.

Flow rate is another standout, a homeowner who had the boiler fitted in a loft extension reported a noticeable boost in shower pressure. Several owners of the 835 model echo this, describing hot water delivery as strong and reliable.

Long-term confidence in the brand plays a role in purchase decisions too. A number of reviewers chose the ecoTEC Exclusive partly on the strength of previous Vaillant boilers lasting well over a decade. The 10-year warranty, available when installed by a Vaillant-registered engineer, is frequently cited as a major draw.

Negative reviews

Reliability is the main concern raised by dissatisfied owners. An owner of the 835 model described the boiler working for just one month after installation before recurring faults set in, leaving her without heating or hot water across two full winters. Despite multiple visits from Vaillant’s engineers, the fault was never permanently resolved, and Vaillant declined to replace the unit under warranty.

Customer support is a secondary but recurring complaint, with one reviewer reporting a Vaillant engineer ending a call abruptly without resolving the issue, while another found that emails to customer service went unanswered.

How the Vaillant ecoTEC Exclusive combi compares

Vaillant ecoTEC Exclusive Combi Comparison Table
Model	Vaillant ecoTec Exclusive combi	Worcester Bosch Greenstar 8000+ combi	Viessmann Vitodens 100-W combi
Typical unit price	£2,000	£1,950	£1,400
Heat exchanger	Stainless steel	Aluminium	Stainless steel
Standard warranty	5 years	8 Years	5-7 years
Max warranty	10 years	12 Years	10-12 years
Built-in WiFi	No (optional via myVAILLANT connect gateway)	No (RF Key for optional thermostat)	Yes
App control	myVAILLANT/vSMART	Bosch EasyControl	ViCare
Cupboard fit	Yes	No (780mm)	Yes
Max output/bathrooms	43kW 2-3 bathrooms	50kW 3+ bathrooms	35kW 2 bathrooms

Final thoughts – is the Vaillant ecoTEC Exclusive combi right for you?

The ecoTEC Exclusive Green iQ is built for long-term durability, featuring a stainless steel heat exchanger engineered for 15-20 years rather than the industry-standard 10-12 years. Worcester uses aluminium heat exchangers, which are lighter and adequate for the warranty period but corrode faster and lose efficiency over time. 

Against the Worcester Bosch Greenstar 8000+ 45kW, the Vaillant delivers comparable performance with higher flow rates (17.8 l/min vs Worcester’s 16 l/min) and superior build materials (stainless steel vs aluminium heat exchanger). The Worcester wins on warranty extension (12 years vs 10 years) and has a full-colour touchscreen display with intelligent automatic filling system that maintains pressure without manual intervention. Both require accredited installers for extended warranties and separate filter purchases.

The critical difference is heat exchanger material. Stainless steel in the Vaillant outlasts aluminium in the Worcester, aluminium heat exchangers typically need replacement at 10-12 years. The Worcester’s 12-year warranty covers this risk; the Vaillant’s 10-year doesn’t but the stainless steel is built to not need it.

For homeowners planning to stay 15+ years and prioritising low running costs, durability, and build quality, the ecoTEC Exclusive Green iQ is one of the strongest premium combi boilers on the UK market. If you value maximum warranty coverage, touchscreen controls, and automatic intelligent filling, the Worcester 8000+ deserves consideration but expect heat exchanger replacement costs beyond year 12. 

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