E.ON Heat is responsible for the flow pipe and return pipe going in and out of the HIU. E.ON Heat is responsible for the Heat Interface Unit (HIU) and Heat meter. The homeowner is responsible for taps, showers and hot water cylinders. The homeowner is responsible for the cold water mains pipe in and the pipework from the HIU, including the external filling loop, heating loop and valves. The homeowner is responsible for underfloor heating, radiators and Thermostatic Radiator Valves (TRVs). The homeowner is responsible for the room thermostat, unless otherwise stated in the supply agreement.