BC Partners has won preferred bidder status to buy Baxi from Electra and Candover, the buy-out firms, in a deal that could value the UK boiler maker at more than £600m (€850m).

Sources close to the auction, run by Merrill Lynch, said BC Partners had beaten rival buy-out firms Bain Capital and Carlyle and trade buyers UTC, a US industrial group, and Merloni Termosanitari, an Italian boiler maker.