Over 900,000 people took part in online interviews conducted by researchers YouGov on behalf of the German business newspaper. Family-run heating innovator Viessmann beat other top-five placing companies Vaillant, Buderus (Bosch), Stiebel Eltron and Junkers (Bosch) to take the top spot.

Graham Russell, managing director of Viessmann UK, commented: “We are always striving to be better for our UK customers and were delighted when this was reflected with Which? Best Buy recognition for the third year running earlier this year.

“To see that this has been mirrored in the German market, where our headquarters is based, demonstrates unequivocally that Viessmann is doing the right things for its customers.”

Brands were evaluated on six performance criteria: general impression, quality, price-performance ratio, customer satisfaction, readiness to recommend and employer image. Viessmann scored 34.9 points – 3.2 higher than second place Vaillant and 8.7 more than Junkers, which ranked fifth. In total, 18 heat and energy companies had sufficient brand recognition to be evaluated.

The consumer interviews took place between September 01 2018 and August 31 2019. The findings are representative of the views of the German population over 18 years.