| 165 / | HD | HEAT EXCHANGE |
| DIG 327 | DD | THERMOSYPHONIC HAVING VERTICAL AIR DRAFT PASSAGE {3} |
| DIG 337 | | .~ Heating or cooling means entirely surrounded by air draft passage forming casing {3} |
| DIG 338 | DD | .~.~> Nested or concentric members define annular air draft passage and heating or cooling conduit {1} |
| DIG 340 | DD | .~.~> Including flow baffle in casing |
| DIG 341 | DD | .~.~> Parallel heating or cooling tubes or tubular sections (e.g., coil, serpentine, etc.) |