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ecoTEC sustain 24, 28 & 34 kW

Specification combination boiler range

  • Designed for specification in the social housing market
  • Quiet Mark awarded
  • High efficiency ErP 'A' rated product
  • High quality stainless steel heat exchanger designed for long life and easy maintenance
  • New condensate trap with safety back-up
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Combination boiler range

The ecoTEC sustain is designed for specification with easy use, longevity and low maintenance firmly in mind.

The ecoTEC sustain boiler range of combination boilers feature a high-quality stainless steel heat exchanger, designed with front access for ease of service, resulting in less time and money spent on repairs and ensuring your peace of mind.

The range features 24,28 and 34kW combination models to suit all types of properties.

Key features and benefits

  • Compact dimensions - 720mm (H) x 440mm (W) x 338mm (D) For flexible siting options
  • High-quality heat exchanger - Stainless steel heat exchanger designed for long life and easy maintenance
  • Removable side panels and push-fit flue system - For improved accessibility and ease of installation
  • Modulating low NOx burner and fan - Lower emissions to fulfill green credentials
  • Recognised Grundfos high-efficiency pump - Modulating high-torque pump uses low energy to deliver a balanced output to meet the boiler demand, helping to reduce energy consumption
  • New condensate trap with safety back-up - Removable from the base of appliance for easy install and maintenance
  • Large illuminated blue on back LED display - Easy-to-read boiler display wherever it is sited with simple fault code identification
  • Compatible with aroTHERM air-to-water heat pump hybrid system - Making the perfect entry into renewable systems
  • Familiar footprint and flue position - Makes replacing an existing ecoTEC pro with an ecoTEC sustain quicker and easier; compatible with all existing Vaillant flue components
  • Controls compatibility - The wide range of Vaillant room thermostats, wired and wireless controls including the vSMART™ app-based control with weather compensation to lower running costs.
  • ErP A rated product - Suitable for both refurbishment and new build with lower running costs.



Technical dataUnitecoTEC sustain 24ecoTEC sustain 28ecoTEC sustain 34
Boiler type CombiCombiCombi
LPG convertible YesYesYes
Article number 001001998000100199810010019982
PCDB number 181181811918120
Boiler Dimensions (H x W x D)mm720 x 440 x 338720 x 440 x 338720 x 440 x 338
Side clearancemm555
Top clearancemm165165165
Top clearance if using rear fluemmN/AN/AN/A
Bottom clearancemm180180180
Front clearance * mm500500500
* can be reduced to 5mm if fitted behind removable door/panel    
Nominal heat output range 50/30°c (condensing mode)kW7.0 - 20.18.0 - 20.19.1 - 19.9
Nominal heat output range at 80/60°c (non-condensing mode)kW6.4 - 18.57.4 - 18.58.4 - 18.5
Flow temperature range°c30 - 80 30 - 8030 - 80
Modulation (max/min)1 : X1:3.81:3.81:4
Domestic Hot Water 
Maximum heat output for water generationkW24.328.134.0
Lowest water pressure to operate boilerbar0.30.30.3
Lowest water flow for operationl/min1.71.71.7
Domestic hot water flow rate (at Δ35˚C)* l/min9.911.614.1
Hot water output temperature range˚C35-6035-6035-60
* Vaillant combi boilers are fitted with a flow regulator set to achieve a temperature rise of 42°C.
This maintains comfortable bathing and showering during the colder months of the year.
Gas inlet connection (pipe size)mm151515
Heating flow and return connections (pipe size)mm222222
Hot and cold water connections (pipe size)mm151515
Heat exchanger materialStainless/AluminiumStainless SteelStainless SteelStainless Steel
Filling loop suppliedYes/NoNoNoNo
Boiler lift weight (dry)KG30.830.832.8
Spacer frame availableYes/NoYesYesYes
NOx (En 15502-2-1)mg/kwH32.834.231.1
ErP efficiency%929292
ErP decibel rating (sound power)dBa494843
PCDB seasonal efficiency (SAP 2009/2012)%
Flueing Options 
Maximum horizontal flue length 60/100m9910
Maximum vertical flue length 60/100m101011
Maximum horizontal flue length 80/125m232831
Maximum vertical flue length 80/125m232831
Rear flue optionsYes/NoNoNoNo
Permissible flue classifications C13, C33, C43, C53C13, C33, C43, C53C13, C33, C43, C53