Over the past three decades, Air Diffusion Agencies has grown from a single-location business into a national leader in the HVAC industry. Founded in 1989 by Bill Threadgold, the company began its journey at 101 Frederick Street, Welland, South Australia. With a strong focus on quality, innovation and customer service, the business quickly expanded its footprint.
In 1998, a second branch was opened in Adelaide’s southern suburbs at Lonsdale, followed by a third in Darwin in 2000. The momentum continued with a fourth branch in Salisbury in 2001, which later became home to a new factory warehouse in 2003.
By 2004, Air Diffusion Agencies had begun importing products from China, further strengthening its supply capabilities. In 2007, the Lonsdale branch relocated to a larger site on Roxburgh Avenue, and in 2009, the Welland location expanded to include 99 Frederick Street with a new warehouse.
The company’s national reach grew in 2010 with the opening of a fifth branch in Queensland at Acacia Ridge. Strategic acquisitions followed: in 2014, Connect Air was acquired in Beverley and in 2015, Fibre Co was acquired in Athol Park, specialising in polyester insulation.
2017 marked a year of major expansion. The Welland branch grew again, acquiring 105–109 Frederick Street, which became the new home for the sheetmetal and ductboard facility relocating from Beverley. That same year, the polyester plant was upgraded and moved from Athol Park to Beverley, where manufacturing began in 2018.
Also in 2018, the Darwin branch relocated to a new site at 116 Winnellie Road. In 2020, the Lonsdale branch expanded further with the acquisition of 15 Roxburgh Avenue.
In 2023, Air Diffusion Agencies acquired Paltech Victoria, adding three new locations in Knoxfield, Thomastown and Bendigo. This expansion continued in 2024 with new Paltech stores opening in Pakenham (August) and Truganina (December).
In 2025, the company continued its national expansion with the opening of a new branch in Eagle Farm, Queensland – strengthening its presence in the Sunshine State.
In November 2025, Air Diffusion Agencies Pty Ltd will enter a new chapter. To reflect its national presence and proudly Australian-owned status, the company will begin trading as Air Diffusion Australia.
This transition marks not just a change in name, but a celebration of over 30 years of growth, innovation and commitment to the HVAC industry across Australia.
