ecoTEC exclusive Green iQ 835, 843

ecoTEC exclusive combination boiler

  • Wide modulation range of up to 1:10
  • Extra-condense heat exchanger
  • Up to 17.8 l/min flow rate
  • High power, 43kW output model available
  • 7 year warranty available with options up to ten years when registered by an Advance installer


The new ecoTEC exclusive Green iQ is our first ever boiler product with the power of Green iQ technology.

Combining our complete range of smart technologies and features, you can be sure you’re receiving the very best when you have a new ecoTEC exclusive installed. As well as providing great performance, the new ecoTEC exclusive intelligently manages consumption and output to keep all its components running at peak performance, for longer, providing a low-maintenance solution that you can rely on.

The ecoTEC exclusive range consists of two large output combination boilers with Extra-Condense technology, and a single system boiler, which includes an integrated diverter valve for the first time in UK Vaillant history.

Features and benefits:

  • Wide modulation range of up to 1:10 - adapts perfectly to every situation, therefore your ecoTEC exclusive boiler will not use any more energy than it needs to - ensuring fuel bills are kept to a minimum
  • Extra-Condense heat exchanger - taking overall combi boiler efficiency to the next level – offers the highest efficiency levels to reduce energy bills
  • Green iQ Mode - outstanding eco-credentials from Vaillant’s latest boiler range, which optimises running cycles, results in even lower gas consumption and the boiler is highly recyclable (85%) at the end of its life
  • High power, 43kW output model available - delivers Vaillant’s highest ever flow rate of 17.8 l/min
  • Compatible with Vaillant’s vSMART™ heating control - when a vSMART control is added the ecoTEC exclusive will achieve an A+ ErP rating, making it welcome in any switched-on, energy-conscious home
  • Standard 2 year warranty, can be upgraded to a 7 year warranty when registered by a Vaillant Advance installer
  • Option to purchase extended warranty up to 10 years when registered by an Advance installer



ecoTEC exclusiveecoTEC exclusive 835ecoTEC exclusive 843
Article number 00100170640010017065
Maximum heat output for water generation (kW)35.343.4
Nominal heat input for Central heating (kW)3.6 - 24.8
(LPG: 8.0 - 24.8)
4.5 - 33.7
(LPG: 8.0 - 33.7)
Heating setting range (kW)
4 - 25

5 - 34
Max. Flow temperature (°C)8585
Expansion vessel capacity (l)1010
DHW mode
Lowest water volume for operation (I/min)1.51.5
DHW performance (at DT=∆35K) (I/min)14.517.8
Hot water output temperature range (°C)35 - 6535 - 65
Nox (mg/kWh)34.936.8
ErP efficiency94%94%
ErP Rating (Heating/Hot Water)A/AA/A
Boiler dimensions (H x W x D)720 x 440 x 406 720 x 440 x 474

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