Tecogen Inc. designs, manufactures, sells and maintains cogeneration products, including combined heat and power (CHP), air conditioning systems and water heaters for residential, commercial, recreational and industrial use. The Company is engaged in the business of manufacturing and supporting CHP products based on engines fueled by natural gas. The Company manufactures over three types of CHP products, such as cogeneration units that supply electricity and hot water, chillers that provide air-conditioning and hot water, and water heaters. Its commercial product line includes the InVerde, InVerde e+ and TECOGEN cogeneration units; TECOCHILL chillers; Ilios high-efficiency water heaters, and Ultera emissions control technology. Its customers include hospitals and nursing homes, hotels and motels, office and retail buildings, and military installations. Its cogeneration systems and chillers use the engine, the TecoDrive 7400 model.