| 摘要 |
<p>The arrangement is intended for recovering heat from the combustion gas passing through the natural-draught flue duct (2,3) of a central heating boiler or the like. It comprises a by-pass duct (5) which is connected to the duct (2,3) at two vertically spaced points (6,7) and contains a heat exchanger (8) with flow and return lines (9,10) for water and a circulation fan (11). The by-pass duct may communicate with a duct section (4) connecting the lower (2) to the upper (3) part of the flue. This section may be double-walled, the inner wall having two vertically spaced ports connecting with the beginning and the end respectively of the by-pass duct. FL.</p> |
