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Vaillant ecoTec Plus 938 Storage Combi Boiler – Review

Vaillant’s ecoTec Plus 938 is a popular choice for those with mid-sized properties. Founded in Germany in 1874, Vaillant is Europe’s second largest boiler manufacturer, while directly competing with Worcester Bosch. High quality and polished German-engineered energy products all sit within Vaillant’s product lines.

In today’s review, we’ll be focusing on the Vaillant ecoTec Plus 938 combi boiler.

Will the Vaillant ecoTec Plus 938 be suitable for my home?

The Vaillant ecoTec Plus 938 is designed for larger homes with high hot water demand, especially those with 1/2 bathrooms and up to 4 bedrooms. The 938 comes fully installed with an integrated water storage device, which can deliver a flow rate of up to 15.9l/m, as well as a central heating output of 28.9kW and hot water output of 38kW.


Most modern combination boilers on today’s market come with a very standard control panel with basic controls for your boiler. Hidden away by a flap, the 938’s control panel allows you to increase/decrease the boiler’s output and switch your boiler on or off. The display will show any fault codes, which can be used to diagnose any issues with your boiler if it were to break down or run into any faults. With modern boilers, it’s now easier for engineers to be able to diagnose issues quickly without the need for opening up the boiler. Due to error codes and the easy access to components within the boiler, the cost of call-outs has been reduced significantly. In the case of the ecoTec Plus 938, parts are easy to find and replace, and the build of the boiler is relatively simple despite the addition of the small storage unit.

Seeing as the boiler’s onboard controls won’t be enough to control and take advantage of your central heating system properly, Vaillant offer a vast range of controls from mechanical room thermostats to smart thermostats. Smart thermostats are a modern and techy alternative to the traditional programmable thermostat, allowing you to control your heating and hot water from your smartphone, tablet or PC.

Smart thermostats offer the latest in home automation with highly intelligent technology and great features, including the ability to control your central heating from your smartphone. The app that comes bundled with a smart thermostat will allow you to make changes to your heating settings, switch your heating on or off whether you’re at home or away, and monitor your energy use. If you’re not sure about the upgrade to a smart thermostat, wireless programmable thermostats are your best bet.


The ecoTec Plus 938 measures at 720x440x600mm, which is quite large considering the smaller and compact nature of most other combination boilers. The 938 is larger due to the additional small water storage tank at the back of the boiler.


Each model in Vaillant’s ecoTec boiler range comes with a standard 5-year warranty that can be extended by a further 5 years with an accredited installer. At Hometree, you can benefit from extended warranties up to 10 years as standard with every boiler.

Energy Efficiency

The 938 is an A-graded boiler, which means it’s highly efficient with excellent performance and reduced carbon footprint. With an ErP (Energy-related Products) rating of 89.3%, you can expect incredible performance and savings on your energy bills.

Before energy products enter the market, the ErP directive actively tests energy products to ensure that they pass specific criteria for efficiency. If a boiler fails the ErP’s tests, the directive will stop the boiler from being made available for sale, while making recommendations for design improvements to reduce the amount of energy wasted.


The Vaillant ecoTec Plus 938 is perfect for medium to large-sized homes, especially if you have two bathrooms with a shower/bath installed and up to 4 bedrooms. The ecoTec Plus boiler range offers both energy efficient and high-quality boilers, reducing energy wastage. The ecoTec Plus boiler range is also QuietMark accredited, meaning that they are low in noise output due to their design.

 Vaillant ecoTec Plus 938 Storage Combi
ErP rating (energy efficiency)A (89.3%)
Size (HxWxD in mm)720x440x600
Heating output (kW)28.9
How water output (kW)38
Flow rate (litres/min)20
Standard warranty (years)5 (extended warranties available)
Other available sizes (kW)25, 32, 35

Which? boiler review

The consumer group Which? review each boiler on the market to find the most (and least) reliable boilers according to a survey completed by thousands of boiler owners. In each review, Which? supply a brand score percentage and star ratings for each category. Take a look at the Vaillant ecoTec Plus 938 Storage combi boiler rating below:

Which? Score 
Efficiency rating★★★★★
Brand reliability★★★★☆
Brand customer score★★★★★
Ease of repair★★★★★
Ease of service★★★★★
Availability of parts and spares★★★★★
Build quality★★★★★
Engineer recommendation★★★★★
Brand score80%

Boiler manual

Vaillant ecoTec Plus 938 Storage Combi boiler manual

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