| 摘要 |
<p>A heating installation comprises a fluid-flow pipework circuit with at least one heater 6, fluid-flow through the or each heater being controllable by a respective valve 9, the or each valve being controllable by an electrical resistance. In a previously proposed system one end of the or each resistance is electrically connected to a power source via the pipework, the other end of the resistance being connected to the source by a cable. The present invention seeks to dispense with the cable(s) and each end of the or each resistance is electrically connected to a respective section of the pipework circuit, the sections being electrically isolated from each other by a member 15 and arranged to supply current to the or each resistance from a source 18. <IMAGE></p> |
