Vaillant ecoTEC exclusive

At a glance

• Configurations: Combi, System
• Best suited to: Homes wanting premium hot-water performance and controls
• Fuel: Mains natural gas (some variants are LPG-convertible, check the manufacturer’s data).

Specifications

Match the badge in front of you to a row before you use any of this. Every figure below was read from the Vaillant literature listed under Sources at the foot of this page, checked 6 September 2026. Outputs, variants and part numbers change by year, so the appliance data plate is still the last word.

Case size: 720 x 440 x 406 mm on the 835, 474 mm deep on the 843. Weight: 47.5 kg on the 835 and 55 kg on the 843.

• Vaillant quotes 14.5 to 17.8 l/min at a 35 K rise across the two exclusive combis, with the 843 at 17.8. Modulation is 1:10.4 on the 835 and 1:10.1 on the 843.
• The 843 is the highest output combi Vaillant sells. Guarantee is 5 years out of the box, up to 10 through the installer scheme when fitted with a filter.

Where the data plate is

Data plate on the underside of the boiler. The serial number is on a plastic label behind the front flap and repeated on the data plate.

Worth knowing on site

• Sits at the top of the ecoTEC family.
• Often paired with Vaillant's smart controls; check compatibility on the manufacturer's site.

On the tools

Sitting above the ecoTEC plus, the exclusive is the range engineers reach for when a customer specifically wants Vaillant's higher-end hot-water performance and controls. It is less commonly seen than the plus, simply because fewer installs call for the top tier.

Variants and configuration

Available in combi and system form, the exclusive is generally paired with Vaillant's smart controls, so installs often include more time setting up and demonstrating the app or thermostat than a standard ecoTEC plus swap. Compatibility is worth checking on Vaillant's site before quoting.

Where it sits in the range

The exclusive occupies the top of the ecoTEC family, above both the plus and the budget ecoFit pure. It represents Vaillant's premium domestic tier in much the same way Worcester Bosch's 8000 or Ideal's Vogue Max sit above their respective mid-range models.

Finding the manual and the data plate

For the exact outputs, gas rate, dimensions and commissioning figures, work from the appliance’s data plate and the manufacturer’s installation and servicing instructions. The GC (Gas Council) number and serial are on the data plate, usually behind the front panel or on the underside. Vaillantpublishes its manuals and support at Vaillant support.