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ecoTEC exclusive with Green iQ

  • The best in boiler performance, control and efficiency
  • Fully compatible with our vSMART™ heating control for optimum performance and smartphone app control
  • Eco-friendly and 85% recyclable
  • Hand-assembled in our award-winning Derbyshire manufacturing plant
  • 5-year guarantee as standard, with 7 years available when you book a Vaillant Advance installer or 10 years when fitted with a Boiler Protection Kit by a Vaillant Advance installer*


*10 year guarantee only available on boilers with an output of up to 45kWs

The pinnacle of the Vaillant boiler range, ecoTEC exclusive is the ultimate in energy efficiency, low consumption and running costs – which is why it carries our unique

Combining our complete range of smart technologies and features, you can be sure you’re fitting the very best when you fit new ecoTEC exclusive. 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 condensate technology, and a single system boiler, which includes an integrated diverter valve for the first time in UK Vaillant history.

Optimum boiler performance, control and efficiency:

  • Staggering modulation of 1:10, which gives the boiler a high level of efficiency with lower fuel bills. The boiler can adapt itself to give only the exact heating output you require ultimately lowering fuel; bills. Much like pressing the gas pedal of your car to adjust power and speed
  • Hand assembled in Derbyshire by one operative from start to finish, in our award winning manufacturing plant.
  • ecoTEC exclusive is 85% recyclable at the end of its life
  • 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
  • Standard 2 year warranty, can be upgraded to a free 7 year warranty when registered through Vaillant Advance
  • Option to purchase extended warranty up to 10 years when registered through Vaillant Advance



Technical dataUnit of measureecoTEC exclusive 835ecoTEC exclusive 843
Boiler type combicombi
Signature model output 35kW43kW
Article number 00100170640010017065
Gas Council number 47-044-6647-044-67
Boiler dimensions (HxWxD) mm720 x 440 x 406720 x 440 x 474
Nominal heat output range at 50/30˚C (Condensing mode)kW3.9 - 26.44.8 - 36
Nominal heat output range at 80/60˚C (Non condensing mode)kW3.4 - 24.64.3 - 33.4
Maximum flow temperature˚C8080
Flow temperature range˚C30 - 8030 - 80
Flow temperature factory setting˚C7575
Approximate condensate volume at 50/30˚Clitres/hr2.483.37
Modulation (max/min)1 : X1:10.41:10.1
Domestic Hot Water
Maximum heat output for water generationkW35.343.4
Lowest water pressure to operate boilerbar0.350.35
Lowest water flow for operationl/min1.51.5
Lowest water pressure for maximum flow ratebar0.80.8
Domestic hot water flow rate (at DT = Δ35K) * l/min14.517.8
Hot water output temperature range˚C35 - 6535 - 65
Expansion vessel sizelitres1010
Gas inlet connection (pipe size)mm1520
Heating flow and return connections (pipe size)mm2222
Hot and cold water connections (pipe size)mm1515
Heat exchanger materialStainless/AluminiumStainless SteelStainless Steel
Boiler lift weight (Dry boiler)kg47.555
NOx class 55
NOx (En 15502-2-1mg/kWh3536
ErP efficiency%9494
ErP decibel rating (sound power)dBa4351
Fluing options
Maximum horizontal flue length 60/100m5.55.5
Maximum vertical flue lengthm88
Maximum horizontal flue length 80/125m3232
Maximum vertical flue length 80/125m3434

*flow restrictor fitted to achieve a Δ42K rise

Related Products

Related Products

VRC 700 / VRC 700f Weather Compensating Thermostats - a Wired or wireless weather compensating programmable room thermostat.

  • Works with our complete range of Vaillant boilers
  • Flexible time programs
  • Works with S & Y plan systems

vSMART™ intelligent room control with app

  • Smart phone app for both Android and Apple iOS application
  • Self learning
  • Weather compensation

VRT 350 & 350f

  • New attractive, easy to use design with blue backlit display
  • Adjusts heating and hot water to British summer/winter time
  • Two temperature setting levels: desired and set-back temperatures