Vaillant EcoTec Plus Review

Vaillant combination boilers 824, 831 and 837

Vaillant ecoTEC Plus 824, 831 and 837 expert and user review. See top features, pros and cons from condensing Vaillant combi boilers.

Vaillant ecoTEC models are high efficiency combination boilers that are designed for combined home and domestic water heating. Eco boilers provide domestic hot water directly through the faucet, and they operate automatically when the hot water tap is open.

All the ecoTEC plus models are SEDBUK Band "A" rated, which guarantees high condensing efficiency and makes these water heaters economical to run. SEDBUK Band "A" is the best possible rating for low carbon emission.

Models from Eco series

There are three models available in Vaillant ecoTEC Plus series and all of them offer great hot water performance:

  • ecoTEC 824 model - provides heating power in a range from 6.7 kW to 19 kW. It is suitable for one bedroom and one bath homes.

  • ecoTEC 831 model - provides heating power in a range from 8.7 kW to 24 kW.

  • ecoTEC 837 - provides heating power in a range from 12 kW to 28 kW. Models 831 and 837 are designed for homes with 2-3 bedrooms and 1-2 bathrooms.

EcoTEC plus Features

vaillant-ecotec-plus-combi-boilerVaillant ecoTEC plus combi boilers are built compact and lightweight, which is the great advantage over cylinder type; they provide easy wall hanging installation.

One of the neat features is the Vaillant's 'AquaComfort' system that provides an instant hot water at the constant temperature. As the water flow might changes during the time, fully modulating low NOx burner adjusts its output so the water exits with the temperature with the minimal fluctuations.

EcoTEC plus combi boilers are equipped with the 10 L expansion vessel and water pump, making it suitable for closed systems and faster water delivery. Vaillant gas boilers are factory installed to use natural gas, but if your fuel selection is propane or LPG, they can be easily converted. For gas conversion or service, it is a must to contact a qualified technician.

Behind the front flap at the front of the boiler you will find an advanced electronics system. What you will find there are the control buttons and digital display. The built-in status and diagnostic display give all sorts of information; for easy control, monitoring, diagnostic, troubleshooting and servicing. It also gives you an option to use buttons for programming.

When your ecoTEC boiler is working properly, multi functional display system shows the existing water temperature and the pressure gage, pressure in the heating system. If there is a problem with water heating an error code appears on the LCD display. The display also shows when your gas valve is activated, the internal pump is running, when the Warmstart is active or fan speed malfunction.

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  • Modern and attractive design that is perfect for kitchen installation.

  • Vaillant ecoTEC plus combination boilers are equipped with a Warmstart system that provides hot water at the required temperature instantaneously.

  • All combination boilers from ecoTEC plus series are equipped with the high quality heat exchanger, made of the stainless steel. Its large surface provides an increased heat transfer.

  • Built-in two stage frost protection. If the heating water temperature drops below 5 C and the system is in ON position, the boiler will start and heat the water to 30 C.

  • Special flow sensor ensures constant hot water temperatures over a wide operating range.

  • It uses push-fit telescopic flue for safe and easy exhaust termination.

  • To prevent energy waste the boiler uses an anti-cycling economizer control.

  • Very quiet operation.

  • Vaillant ecoTEC plus models are compatible with controls, such as the wireless programmable thermostats, or weather compensated controller that adjusts the boiler hot water output based on the outside temperature.

Pros and cons


  • EcoTEC combi boilers are extremely quiet in operation.

  • All the boiler elements are built to last and are reliable, including small knobs on the control board.

  • It uses the fluctuation to adjust the heat output relative to the water flow changes.

  • The exhaust vent is flexible.

  • It works great if installed professionally.

  • For users who had to switch from cylinders to tankless, on demand technology is praised.

  • Installation is easy.

  • Good hot water flow rates.


  • Issues with the rubber pipe; it bursts often. This is one of the reasons why they are not included in the latest generation of ecoTEC boilers.

  • Bad quality of water pumps (older models). Many complaints that water pump had to be replaced, and that replacement was complex.

  • Expensive.


Vaillant ecoTEC plus boilers, 824, 831 and 837 models are condensing combination boilers that do not require the hot water cylinder or cold water tank. Designed as the condensate boilers they come with the improved energy efficiency which is great on your pocket and with the lower emission good on the environment. They are actually using heat from fumes to heat water so the efficiency raises to over 90%, compared to 70-80% for standard type. They come with the two year warranty and most of the time faulty components will be replaced as long as the installation was done professionally.

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