A fuel-fired appliance with thermoelectric-powered secondary electric heating has a burner providing hot combustion gasses into a first housing. A second housing containing a fluid receives heat from the combustion gasses in the first housing. A thermoelectric device attaches to a surface of the appliance heated by the combustion gasses and generates a voltage. An electric heating element is in thermal communication with the second housing, and the electric heating element is electrically connected to the thermoelectric device.

A free-standing Energy Recovery System enables sanitary recovery of thermal energy with heat transfer from hot waste effluent to incoming domestic water. The source of the effluent may, for example, be conventional commercial ware-washing, clothes washing equipment, pasteurization and other industrial processes.

A cogeneration system has a fuel cell, a fuel cell system, and an indirect supply line. The fuel cell system has a first heat exchange unit, a heat storage tank, and a waste heat recovery line. The first heat exchange unit is positioned close to an outer side of the fuel cell or inside thereof and causes a heat medium to recover heat generated at the fuel cell. The heat storage tank stores the heat medium and provides heat in response to a hot-water supply demand. The waste heat recovery line causes the heat medium to circulate between the fuel cell and the heat storage tank. The indirect supply line includes a second heat exchange unit that supplies heat by causing the heat medium stored in the heat storage tank and a medium to exchange heat with each other.

The invention relates to a floor drain comprising a drain compartment having a bottom, at least one side and an open upper portion. The bottom and the at least one side together define a space to collect waste water. The bottom comprises an opening for a drain trap. The floor drain further comprises a heat exchanger element, receivable in the space of the drain compartment, for transferring heat present in the waste water to fresh water. The heat exchanger element is provided with a first connection and a second connection. The first connection and the second connection are arranged inside the space of the drain compartment. A first conduit is connected to the first connection and a second conduit is connected to the second connection.

A power generation system of the present invention includes: a fuel cell unit (101) including a fuel cell (11) and a case (12); a controller (102); a combustion unit (103) provided outside the case (12) and configured to combust a combustible gas to supply heat; and a discharge passage (70) configured to cause the fuel cell unit (101) and the combustion unit (103) to communicate with each other, wherein in a case where an exhaust gas is being discharged to the discharge passage (70) from one of the fuel cell unit (101) and the combustion unit (103) and the controller (102) changes the flow rate of the exhaust gas discharged from the other unit, the controller (102) controls at least the flow rate of the exhaust gas discharged from the other unit such that the flow rate of the exhaust gas discharged from the one unit becomes constant.

A heat exchanger that includes a portion for heat exchange with gray water, a portion for heat exchange with clean water, the heat exchanger being arranged to transfer heat between the gray water heat-exchange portion and the clean water heat-exchange portion during a distribution of water and thereby heat a feedwater to a first temperature, wherein the heat exchanger includes a first heating means arranged to achieve the heating of the feedwater, for heating the feedwater to a second temperature, and wherein the heat exchanger includes a second heating means arranged to keep the clean water heat-exchange portion at a temperature greater than or equal to the first temperature during a period without water distribution.