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ecoFIT sustain 25, 30 and 35kW

Specification combination boiler range

  • Designed for specification in the new build and social housing market
  • Compact cupboard fit with rear flue option
  • High efficiency ErP 'A' rated product with strong SAP ratings
  • Compatible with the full range of Vaillant controls and accessories
  • High quality lightweight aluminium heat exchanger with excellent power to weight ratio


Combination boiler range

The ecoFIT sustain range of combination boilers offers an excellent size-to-output ratio, providing 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 homeowner and tenant properties.

Key features and benefits

• Compact, cupboard fit solution – A smaller boiler footprint (702mm x 390mm x 295mm) means the ecoFIT Sustain offers siting flexibility, including cupboard fit

• Top and rear flue options - For flexible siting options in a wide variety of properties

• High SAP performance - Helps reduce new build cost. 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 1:5 - Ensuring low energy consumption and maximum efficiency

• Clear bright LCD display - Easy to read boiler wherever it is sited

• Up to 10m flue lengths - Allows maximum flexibility for location of the boiler

• Controls compatibility - 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 heating bills



Technical dataUnit of measureecoFIT sustain 825ecoFIT sustain 830ecoFIT sustain 835
Boiler type systemsystemsystem
Signature model output 25kW30kW35kW
Article number 001002039200100203930010020394
Gas Council number 47-044-7147-044-7247-044-73
Boiler dimensions (HxWxD)mm702 x 390 x 295702 x 390 x 295702 x 390 x 295
Nominal heat output range at 50/30˚C (Condensing mode)kW5.3 - 19.16.3 - 19.17.5 - 19.1
Nominal heat output range at 80/60˚C (Non condensing mode)kW5.1 - 18.36.1 - 18,37.2 - 18.3
Maximum flow temperature˚C808080
Flow temperature range˚C10 - 8010 - 8010 - 80
Flow temperature factory setting˚C757575
Approximate condensate volume at 50/30˚Clitres/hr1,531,841,84
Modulation (max/min)1 : X1:41:51:5
Domestic Hot Water  
Maximum heat output for water generationkW25,730,635,7
Lowest water pressure to operate boilerbar0,30,30,3
Lowest water flow for operationl / min1,91,91,9
Lowest water pressure for maximum flow ratebar111
Domestic hot water flow rate (at DT = Δ35K)l / min10,412,214,1
Domestic hot water flow rate (at DT = Δ42K)*l / min8,210,412
Hot water output temperature range˚C35 - 60 35 - 6035 - 60
Expansion vessel sizelitres888
Gas inlet connection (pipe size)mm151515
Heating flow and return connections (pipe size)mm222222
Heat exchanger materialStainless/ AluminiumAluminiumAluminiumAluminium
Boiler lift weight (Dry boiler)kg222222
Maximum horizontal flue length 60/100m151515
Rear flue optionsYES / NOYesYesYes
Permissible flue classifications C13, C33, C43, C53C13, C33, C43, C53C13, C33, C43, C53
NOx class 555
NOx (En 15502-2-1)mg/kWh38,938,337,2
ErP efficiency%939393
ErP decibel rating (sound power)dBa494445
PCDB seasonal efficiency%89,389,389,3

*Via fitment of a flow restrictor