| 摘要 |
<p>Pre-heater for hot water supply boiler of a central heating system recovers heat that would otherwise be wasted. The pre-heater is placed round the flue pipe, to absorb heat from the flue gases of the oil- or gas-burning boiler, e.g. a boiler which generates steam and is permanently at a high temperature. Flanges separate the heater from the boiler, and for reasons of safety a pump controlled by a thermostat withdraws water for cooling if too little had been drawn off. The usual safety devices are incorporated in the cold water supply to the pre-heater.</p> |
