| 摘要 |
<p>The heating boiler has a hearth for burning solid fuel, a fan for supply of combustion air to the hearth, and at least one exhaust gas duct connected to the hearth for heat exchange with a heat carrier, and for conducting exhaust gases away from the boiler. A control regulates the fan speed, and comprises a spirally-wound bi-metal spring fitted in the exhaust gas duct. One end of the spring is firmly attached to the conduit wall, whilst the other end is fixed to a rotatably located shaft. On the shaft is arranged an electrical rotary rheostat or thyristor connected to the current circuit feeding the fan motor. The shaft also carries an eccentric which activates a micro-breaker, opening and closing the circuit to an electrically operated damper. (Provisional Basic advised week 83/46).</p> |
