The equity-only transaction generated a gross internal rate of return of 22 per cent for Riverside, which acquired the Cheshire-based business in 2005 in a buy-out from multinational General Electric, a statement from the firm said. The investment had involved two Riverside funds: the North America-based Riverside Capital Appreciation Fund and the Riverside Europe Fund.

Sentinel supplies treatment products to improve the performance and efficiency of residential heating and hot water systems, and has operations in the UK, France, Germany, Italy and the US. Sentinel’s products are sold through builders’ merchants for use by plumbing and heating professionals, and can yield annual savings on household heating bills and lower CO2 emissions.

Led by chief executive Gary Roebuck, the business aims to expand into further markets across Europe through acquisitions following the deal.

Charles Elkington, a partner at mid-market fund manager Electra, comments, ‘With regulation and energy efficiency targets as the key drivers, our strategy will be to grow the company organically, through greater market penetration in Europe and new product development, and by acquisition.’

Riverside managing partner Suzy Kriscunas adds, ‘We harnessed Sentinel’s potential, working with management to expand the company’s strong UK position, build sales channels in Benelux, France, Italy and Germany and initiate sales in the US. Sentinel is well positioned to build on this strong growth foundation going forward.’