In 1985 Atag took over the production of central heating appliances from Benraad in Terborg. The manufacturer of unit air heaters in Winterswijk did not fit in with the new owner’s strategy so the factory continued as an independent company under the name Winterwarm.
Meanwhile they focused again on their core-business: developing, producing and selling indirect fired unit air heaters. Winterwarm continued to sell the unit air heaters under 2 brand names (Benraad heaters changed to Winterwarm heaters) as they each had their own sales channels. With both brand names added together Winterwarm became market leader in the years to follow. Also the part in the turnover realized through exports increased. In 1992 Winterwarm obtained as one of the first companies in her branche the ISO 9001 quality certificate (in 2001 the 2000-certificate was added).