Vaillant ecoTEC plus

At a glance

• Configurations: Combi, System, Regular
• Best suited to: Small through to large homes, depending on output
• 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 352 mm on the 826 to 836, 386 mm deep on the 840 and 580 mm deep on the 940 storage combi. Weight: 36 to 37 kg dry on the 826 to 836, 41 kg on the 840 and 60 kg on the 940.

• Vaillant also quotes a specific flow rate at a 30 K rise, which is the headline number on the brochures: 12.4, 15.2, 17.0, 19.0 and 21.0 l/min for the 826, 832, 836, 840 and 940.
• Vaillant fits a flow limiter to every combi, set to hold roughly a 42 K rise: 8.7 l/min on the 826, 10.4 on the 832, 11.7 on the 836 and 14.0 on the 840 and 940. That is closer to what you will measure at the tap than the brochure figure.
• Guarantee is 5 years as standard, up to 10 through a myREWARDS installer with a protection kit, and the boiler has to be registered within 30 days of installation or the cover drops to 12 months.

Where the data plate is

The current range carries two data plates: the main one on the rear of the electronics box and a second on the top of the boiler. The serial number is on the underside of the front panel and repeated on the data plate. On the earlier ..6/5-5 generation the data plate is on the underside and the serial sits on a plastic label behind the front flap.

Worth knowing on site

• Combi outputs commonly span roughly 25kW to 38kW, with higher-output and system/regular options.
• The range was remastered in the mid-2020s (model numbers such as 826/836 replacing 825/835).

On the tools

As Vaillant's core, most widely specified range, the ecoTEC plus is common enough that most engineers will have fitted several. The mid-2020s remaster is worth checking for on the data plate, since which model number is fitted affects which manual and parts list applies.

Variants and configuration

The plus spans combi, system and regular formats across a wide output band, roughly 25kW to 38kW on the combi side, plus higher-output and system or regular options. That range means two ecoTEC plus installs can serve very different sized homes, so always confirm output from the data plate.

Where it sits in the range

Sitting in the middle of the ecoTEC family, the plus has long been Vaillant's mainstream range, with the budget ecoFit pure positioned below it and the premium ecoTEC exclusive above. The mid-2020s model refresh kept that same three-tier structure in place.

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.