Energy company Flowgroup has revealed "one of the world's largest energy companies" has a signed a contract to test the innovative 'Flow' household boiler.AIM-listed Flowgroup has designed the boiler so that while it heats the home it also generates electricity, known as CHP or combined heat and power.Chief executive Tony Stiff said: "I am delighted to announce that a major international energy company wishes to formally assess the potential of the Flow boiler."He said the potential partner, which operates across all major energy markets and is a "major European energy player", would conduct an initial test and evaluation of a Flow boiler at its own facilities, which supported the Flowgroup's objective of launching its products across the continent.The market for gas-fired heating products in Europe is roughly 8m units per year, with many key markets such as Germany, Italy, France and Netherlands providing incentives and regulations for low carbon heating that could make the Flow boiler a more competitive product than standard boilers.Stiff added: "Flow has developed its technology with the objective of expanding into Europe, North America and Asia. These markets represent opportunities for strong potential future growth and we are pleased to be making this announcement about an initial evaluation programme with an important European player."Shares in Flowgroup were up 4.1% to 39.94p at 08:40 on Wednesday.