ecoFIT sustain 25, 30 & 35kW

Social Housing combination boiler range

  • Designed for specification in the social housing market
  • High efficiency ErP 'A' rated product
  • High quality lightweight aluminium heat exchanger with excellent power to weight ratio
  • Cupboard fit with rear or top flue option
  • Modulating high torque pump uses low energy


Combination boiler range

The ecoFIT sustain range of combination boilers offers an excellent size-to-output ratio, giving your tenants great comfort whilst ensuring a small footprint. Use of sustainable materials also means the boiler is 100% recyclable. The range features 25, 30 and 35kW models to suit all types of tenant properties.

Key features and benefits

  • Cupboard fit - Compact size (702mm x 390mm x 295mm) offers flexibility of siting including the option to cupboard-fit
  • Choice of rear or top flue - For flexible siting options in a wide variety of properties
  • High SAP performance - Helps reduce new build cost by up to 4% on TER. Highly efficient and economical to run up to an 89.3% efficiency rating (SAP 2009)
  • High-quality lightweight aluminium heat exchanger - lightweight, compact design offers long life with an excellent power-to-weight ratio makes installs/maintenance easier
  • Patented 4 sided cooling - Reduces stress on all components to minimise the cost of maintenance over the life of the product
  • Familiar Vaillant diagnostics - Offers quick and easy maintenance for your maintenance team
  • Patented condensate trap - Easy install with a safety back-up
  • Fully modulating low NOx burner and fan - For improved energy efficiency
  • 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
  • Built-in two-stage frost protection - To ensure optimal performance all year round
  • Warm start function - Provides tenants with instant hot water
  • Modulation range up to a 1:4 - Ensuring low energy consumption and maximum efficiency
  • Clear bright LCD display - Easy to read boiler wherever it is sited
  • Best-in-class flue length (up to 10m) - Allows maximum flexibility for location of the boiler
  • Controls compatability - The wide range of Vaillant room thermostats, wired & wireless controls including the vSMART app-based controls with weather compensation to lower running costs for tenants
  • Quiet Mark accredited - Thanks to being ultra-quiet whilst in operation
  • ErP A Rated product - Suitable for both refurbishment and new build with lower running cost to reduce tenant heating bills



25 kW30 kW35kW
Article number 001002039200100203930010020394
Boiler dimensions (HxWxD)mm700 x 390 x 295700 x 390 x 295700 x 390 x 295
Rear flue options YesYesYes
Nominal heat output range at 50/30˚CkW5.3 - 19.16.3 - 19.17.5 -19.1
Nominal heat output range at 80/60˚CkW5.1 - 18.36.1 - 18.37.2 - 18.3
Maximum flow temperature˚C808080
Flow temperature range˚C10 - 8010 - 8010 - 80
Flow temperatue factory setting˚C757575
Approximate condensate volume at 50/30˚Clitres/hr1.841.841.84
Heating range (modulation)kW5.1 - 18.46.1 - 18.47.2 - 18.4
Nominal gas consumptionm³/hr0.5400.6460.762
Domestic Hot Water 
Maximum heat output for water generationkW25.230.035.0
Lowest water pressure to operate boilerbar0.30.30.3
Lowest water flow for operationl/min1.91.91.9
Lowest water pressure for maximum flow ratebar1.01.01.0
Domestic hot water flow rate
(at DT = Δ35K)
Hot water output temperature range˚C35 - 6035 - 6035 - 60
Expansion vessel sizelitres888
Gas inlet connection (pipe size)mm151515
Heating flow and return connections (pipe size)mm222222
Hot and cold water connections (pipe size)mm151515
Heat exchanger material AluminiumAluminiumAluminium
Boiler lift weightkg323333
Maximum horizontal flue length 60/100m101010
Permissable flue classifications C13, C33, C43, C53C13, C33, C43, C53C13, C33, C43, C53
Remaining feed head of pump (at nominal circulation volume and with by pass at factory setting)bar0.250.250.25
ErP efficiency A/AA/AA/A
ErP decibel ratingdBa48.644.444.6
PCDB seasonal efficiency%89.389.389.3